One posabillity for exess oil consumption & backfiring can be a faulty PCV valve (Positive Crankcase Ventilation) valve. this is also posible fault on other vehicles, certainly was on AU Falcons on Gas.

I had to replace the PC Valve on my daughters Hi-Ace Van as well.

When using the recomended 20/50 oil make sure it is the right viscose for you model vehicle.

Regards Jim

First thing I will be asking mechanic tomorrow is about the PCV Valve. I know where it is, Now. Just don't know if anything wrong with it.

patrolst Can you explain more about the viscose. Haven't heard of that. Using a good quality Caltex or is it Castrol (my minds gone blank) 20/50. Haven't seen anything else on label to think about.

After looking at the list I would say most of the items listed are only maintenance catch up. Ive purchased older vehicles & replaced that & more to get the vehicle in a reliable condition. THE killer here is labour 14Hrs @ $60/Hr while not ecessive comes to $840. But if your like me I couldnt aford it either. Whats needed here is a retired & freindly Mechanic.

Hi HW

This is the oil Castrol recommend for your vehicle

CASTROL GTX 20W-50

A bit more about oil's on this link

http://www.valvoline.com.au/pdf/Essential%20Guide%20to%20Motor%20Oil%20Brochure%20FINAL.pdf

A bit more about viscosity from a website.

LUBRICATION 101:

The primary reason for automotive manufacturers to specify relative low viscosity engine oils is for fuel economy, i.e. the thinner the oil (lower the viscosity) the less internal fluid friction there is in the engine and thus less fuel is wasted in overcoming that internal friction.

Viscosity is defined as a fluids "resistance to flow". The higher the viscosity the thicker the oil the more resistant it is to flow.

Most modern engine oils are multi-viscosity, i.e. 5W-30, 15W-50, 5W-50, etc. This is because an internal combustion engine operates in EXTREME temperature ranges. At start up on a winter day the oil may be at 0 degrees, but upon reaching operating temperature the oil may be at 225 degrees.

Lubrication in the engine is primarily "hydrodynamic". Think of a water skier in shallow water that once up on the ski's is kept off of the rough bottom due to the water not being able to flow out from under the ski's as fast as the skier is able to slide up on the water. A car's wheels "hydroplaning" over wet pavement is another example.

If a straight 30 viscosity oil were to be in an engine at 0 degree start-up the engine starter probably wouldn't be able to crank the engine against the oil's viscosity, and if it were able to start the engine there would be oil starvation and damage to the engine due to the 30 viscosity oil not flowing through the engine at 0 degrees. On the other hand if a straight 5 viscosity oil were to be used at start-up it would be OK, but when the oil reached the 225 degree operating temperature the "skier wouldn't be able to stay off the bottom", i.e. the hydrodynamic lubrication would break down (leave the bearings to readily) allowing engine bearing parts to make contact and spot weld at a microscopic level doing severe damage.

All of that being said, oil is formulated with "viscosity index (VI) improvers" to change single viscosity base oils into multi-viscosity oil. A 5W-30 weight (viscosity) oil is actually read as a "5 viscosity winter (W = winter) grade - 30 viscosity summer (S = summer and although not written is implied) grade". It is the VI improvers which allow a single weight oil to behave as a 5 viscosity oil at engine start-up in cold temperatures, but then behave as a 30 viscosity oil at the engine oil's 225 degree operating temperature.

Engine oils are chemically complicated, being formulated with about 15% additives which includes the VI improvers, detergents, dispersants, antioxidants, anti-rust, anti-foamants, anti-wear, etc. The reason for changing oils on a timely basis is due to the fact that the additives are eventually consumed as they do their jobs. The filter removes silicone (dust) and other particulates but does not replenish the additives.

ADDITIVES About 15% of engine oil is additives (synthetics included). These additives are generally as follows:

DETERGENTS Just like laundry soap, they keep the engine clean.

DISPERSANTS These keep the particles that have been cleaned by the detergents suspended in the oil until it is changed.

OXIDATION INHIBITORS They retard oxygen in the crankcase from deteriorating the oil. Oxidation will thicken the oil until it, in extremely high heat situations, literally sets up like tar in the crankcase.

RUST INHIBITORS They react with and neutralize the acids of combustion like sulfur (from the fuel) dioxide which forms sulfuric acid with the water vapor in the crankcase. Sulfuric acid would eat on the engine internals if not neutralized.

ANTIWEAR AGENTS These are typically zinc dithiophosphates. They rapidly react with the metals in the engine to form a thin molecular layer which is relatively softer than the metals. At engine start up, or when shock loading causes moving metal parts to break through the oil film this relative soft reactive layer shears away (and is immediately reactively replaced) instead of metal to metal contact occurring with its resultant spot welding (at a molecular level) which would damage the engine.

FOAM INHIBITORS If oils foam due to the EXTREME turbulence within an engines crankcase the foam will act as an insulator causing the oil, which is a primary engine coolant, to retain the heat it has absorbed from the engine and rapidly damage itself and the engine. These inhibitors lower the surface tension of the oil allowing entrained air bubbles to be released.

POUR POINT DEPRESENTS These block paraffin wax crystal growth at low temperatures thereby delaying an oils gelling.

VISCOSITY Viscosity is the MOST IMPORTANT attribute of any oil. Viscosity is an oils RESISTANCE TO FLOW. To lubricate oil must keep engine parts from contacting one another. A water skier stays on top of the water because at speed the water cant escape from under the ski fast enough to let the skier sink. The same thing is happening within an engine, i.e. the moving parts along with the pressure the oil pump puts up keeps the moving metal parts skiing on top of the oil. This is known as hydrodynamic lubrication. The higher (thicker) an oils viscosity the more resistant it is to flow away from the moving parts its supporting.

VISCOSITY IMPROVERS - Additive molecules which cause an oil to not thin out as readily with temperature increases as it would normally. This is what gives oil its multi weight rating. A 15W-50 multi weight or viscosity oil has ambient temperature properties of a relatively thin 15 (W = winter grade) viscosity oil for quick circulation at cold engine start up, but only thins out as if it were a 50 (implied S = summer grade) viscosity oil when the engine reaches its operating temperature of a nominal 225 degrees.

Heavier/thicker/more viscous oils will consume more fuel due to fluid friction which is why auto manufacturers recommend 5W-30 oils, but Ill trade a little fuel for the greater engine protection a 15W-50 oil, which I use in my 2001 X5, affords anytime. NOTE that up North during the winter a 5W-40 or 5W-50 engine oil may be necessary for cold weather start up.

SYNTHETIC OILS Synthetic oils by definition are "oils produced by synthesis rather than by extraction or refinement". This does not mean that synthetic oils don't start from a basic barrel of crude oil.....they do. It's just that rather than taking the lubricating oil molecules as they naturally occur in the barrel of crude and separating them from the lighter gases (propane), lighter liquids (gasoline) and heavier liquids (asphalt) through "extraction" by solvents or "refinement" by distillation/boiling them off, the lubricating oils from the barrel of crude are chemically modified so as to produce a lubricating oil with a homogeneous molecular structure. Regular oils have a witchs brew of lubricant molecules which also include paraffin. This witchs brew has a nasty tendency to deteriorate by readily reacting with oxygen in the crankcase. Additionally, the paraffin at low temperatures crystallizes and gels the oil which reduces its pour point. Paraffin does the same to diesel fuel #2 at low temperatures and thats why diesel #1 (kerosene), which has much less paraffin, is used up North in winter.

The advantages of synthetic oils are that they flow at relatively lower temperatures (due to not containing paraffin which "gels") and are much more resistant to oxidation degradation at very high temperatures (oxidation causes oil to degrade, thicken and loose their lubricating properties). Because of their chemical stability synthetic oils can withstand longer durations in the crankcase, hence the extended drain intervals that BMW and other manufacturers recommend. The more intensive refining is also much more expensive which the shelf price reflects.


PART 2 - FILTER + API + ENGINE BREAK-IN

FILTER The filter should be able to go the approximate 15,000 miles BMWs service interval lights indicate. I personally drain my filter (of most of the used oil) at an approximate 6,500 miles when I change my oil and replace it at 13,000 miles. If the filter should for some reason become clogged it has a bypass valve which will still allow the oil to circulate to all engine parts.

Regarding how often you should change the engine oil, well it just DEPENDS. If youre only going to drive the vehicle 100,000 miles before you trade it then youll probably never realize the benefits of more frequent oil changes; hand that problem off to the next guy.

On the other hand, if youre like me and plan on driving the vehicle 200,000+ miles then youll want to be diligent in this matter. Oil and additives deteriorate over time (even if the vehicle isnt being driven much, hence the annual change requirement) due to engine heat, oxidation, and reaction with contaminates and engine metals which necessitates filtering and re-inhibiting or changing the oils. Because of the relatively small amount of oil in an automotive crankcase changing it and the filter is much less expensive than re-inhibiting it. If you can do it yourself as I do it really isnt expensive.

The break even point of engine wear vs. $$ again depends upon the conditions the engine endures. Its kind of like describing that normal person ......... who just isnt like any of us. So if your going to keep the vehicle a long time be diligent, but if not, and your conscience will allow you to trade it off to some poor unsuspecting soul, then save the money.

Additionally, engine oils function to remove / distribute engine heat. An aluminum piston melts at around 1,100 degrees F and combustion temperatures above it are around 2,000 degrees F. If oil wasn't constantly sprayed on the under side of the pistons they would melt. Oil also carries the engine wear components which if analyzed on a regular basis will predict maintenance needs prior to a catastrophic failure.

In an engine the only down side to a high viscosity multi-grade engine oil is fuel consumption due to internal fluid friction. It is for this reason that BMW and ALL other vehicle manufacturers recommend 5W-30 engine oils as lower viscosity oils allow them to post higher mile per gallon ratings.

High viscosity multi-grade oils are not a detriment to high revving performance engines either, otherwise BMW would not sell 10W-60 performance oil for their "M" cars. These vehicles rev to 7 grand and are subjected to much "shock loading" (like dumping the clutch), the protection from which comes only in the form of a high viscosity oil, thus the 60 viscosity to maintain hydrodynamic lubrication. Needless to say fuel consumption is not the highest priority for the "M" cars.

In high temperature climates (I live in Houston, Texas) high viscosity multi-grade engine oil is a MUST if one is concerned with engine longevity.

Again, I don't hesitate to swap a little fuel consumption for engine longevity. I have a 2001 X5 4.4i with Dinan engine / transmission software with 62K miles on it. For 22K of those miles I have towed an 8,300 pound GVWR 31 foot Airstream travel trailer with a 900 pound tongue weight (X5 factory rating is 6,000 pounds GVWR and 600 pound tongue weight, go figure). The X5 pulls this load in 5th gear 95% of the time at speeds between an indicated 60 & 70 MPH and RPM varying between 2,000 & 2,400. This high engine loading requires a high viscosity oil and I have used 5W-50 and 15W-50 since the X5 was new. I broke the engine in at relatively light loads and varying engine RPM up to red-line before I ever heavily loaded it. The engine consumes an approximate 1 pint of oil every 6,500 miles at which time I change the oil (since the engine's oil capacity is 8.5 quarts this would equate to a 5 quart engine's oil being changed at around 3,500 miles). I have never had to add make-up oil between changes.

API SERVICE CLASSIFICATION RATING

The API (American Petroleum Institute) forces "performance" conformance through its service classification rating system which you'll find on each quart of oil.

Looking at a quart of Castrol 5W-50 synthetic and a quart of Mobil 1 15W-50 synthetic, they both have "API Service S?/C?" (NOTE: Ive used a ? to indicate the succession of alpha characters used in this position) written in the "Circle" on the bottles. What this means is that although they may formulate their oils using different additives, both oils meet or exceed the API classification and are totally miscible, i.e. you can add one to the other without damaging you engine if you need make-up oil while traveling in an area where your engine oil is not available. If by chance you cannot find synthetic oil you can use a regular oil of the same API classification; additive wise your OK, but you have dumbed down your synthetics durability and pour point and should change it out at the first opportunity.

Incidentally, the S? stands for: "S" = Service (which = service stations, garages etc.) = gasoline engine service and "?" represents the current latest alpha classification that the oil manufacturers MUST meet (started way back in the 1960s as SA, then SB, etc.)

Likewise, the C? stands for: "C" = Commercial (which = fleets, contractors, farmers etc.) = diesel engine service and "?" represents the current latest alpha classification that the oil manufacturers MUST meet (started way back in the 1960s as CA, then CB, etc.).

ENGINE BREAK-IN

All piston engines by design MUST burn some oil because their cylinder walls are wiped with a film of oil by the piston rings during the compression stroke and then this oil film is combusted along with the fuel/air charge during the power stroke.

The break-in process is critical to the rings and their cylinder walls so that they wear-in or "match sand" themselves AND their cylinder walls to one other. This means initially keeping the engine rpm to a relatively low level so that the metal asperities of the rings that contact the asperities of the cylinder walls, generating immense heat at a microscopic level, have enough oil cooling them to carry off the friction heat without "spot" welding themselves together and tearing out a microscopic piece of each other. If this "spot" welding does occur it leaves microscopic pits in the cylinder walls which pool additional oil which is then exposed to the combustion process and burned off.

Additionally, if the match sanding is incomplete because the engine rpm was never high enough to complete the wear-in, then the rings and cylinder walls may never match sand to one another, leaving gaps which dont allow the rings to adequately wipe excess oil from the cylinder walls during the intake and power strokes thus leaving the excess oil on the cylinder walls to be combusted during the power stroke.

SO, the break-in should initially be at relative low rpm to ensure adequate oil cooling of the rings and cylinder walls followed several hundred miles later with some relatively high but short duration rpm excursions to facilitate the match sanding process. After 500 miles or so the duration of the higher rpm excursions can be increased until the wear-in process is complete.

My own 2001 X5 4.4i which has 62K miles on it was broken-in accordingly and I have pulled an 8,300 pound GVWR Airstream trailer for over 22K miles with it (engine rpm between 2,000 and 2,700 with acceleration excursions to 5,500). I use Mobil 1 15W-50 and Im currently due for an oil change since I have about 6,500 miles since the last one, but the dip stick still shows the crankcase to be at the full mark.

Incidentally, above I was discussing only the cylinder rings and walls but all of the moving parts of the engine and drive train go through the same process of match sanding themselves to one another during the break-in period so its critical to an engines longevity that it be done properly. I suspect that the majority of those with oil consumption problems did not break-in their engines adequately.

That being said, for an engine to burn a quart of oil every 2,000 to 3,000 miles would not be out of tolerance. All engines should consume oil since some of the oil that lubricates the piston rings remains on the cylinder walls and is combusted as the piston moves down on the power stroke. A quart every 500 to 1,000 miles would be reason for concern.


PART 3 - SEVERE SERVICE

SHORT TRIPS = SEVERE SERVICE

Vehicles that are primarily driven relatively short distances, i.e. trips that are less than 20 minutes duration, and if more than 20 minutes there are stops where the motor is shut off and allowed to cool down somewhat, especially in a cold climate, are being subjected to SEVERE SEVERCE. What happens is that due to the short duration of the trips the oil is never coming up to full operating temperature of 225 degrees F for an EXTENDED DURATION. The primary product of the combustion of gasoline is water, which on a cold day you see exiting the exhaust as steam. Some of this water is "blown by" the piston rings and ends up in the crankcase where it is absorbed by the oil via a chemical additive known as an EMULISIFIER.

To give you something to relate to, Pine-sol Cleaner is an oil based cleanser which you mix with water prior to use. If you remember, when it is mixed with water it turns WHITE in color. What has happened is that the additive EMULSIFIER in the Pine-sol has caused the water to form microscopic spheres which are held in suspension and make the mixture appear white just as snow appears white due to entrained air within its crystals.

Essentially the same thing is happening in the engine oil. Its EMULSIFIER causes the combustion water blown by the piston rings to be held in suspension in the oil as microscopic spheres. This is good because it keeps the water from settling to the bottom of the crankcase or other low areas in the engine where it readily would promote corrosion and possibly compromise lubrication.

The engine oil EMULSIFIER will release the water only if the engine is brought up to full operating temperature and SUSTAINED there long enough to allow it to boil off. The EMULSIFER, having released the water, is then able to tie up more water the next time the cold engine is started.

If the trips are of short duration and the engine oil EMULSIFER is never allowed to release the water it has tied up by boiling it off the EMULSIFER will eventually chemically separate from the engine oil as a whitish substance (called goop by one poster), and the engine oil will have been severely compromised and MUST BE CHANGED IMMEDIATELY.

Again, a vehicle which is driven on many trips of short duration which dont allow the engine oil to rise to full operating temperature is enduring SEVERE SEVERCE. In this situation you should change the oil at least every 6 months during the summer and every 3 months in extremely cold winter conditions (an alternative would be to deliberately drive the vehicle once every week or so for at least 30 minutes at highway speeds to allow the EMULSIFER to release the water it has tied up).

The BMW X5 manual does not address this situation, and the service interval calculator is obviously not programmed to deal with it.

Idling the engine at start-up only exacerbates the condensation problem because during the entire time the engine is idling the combustion blow-by (primarily water) is being absorbed by the oil emulsifier which has escalated somewhat in temperature but not nearly enough to boil off the water. Then during the first part of a short trip the oil MAY become hot enough to start releasing the water but arrival at the destination and shutting the engine down stops the process.

DONT IDLE!!! Start the engine, let it idle for 30 seconds, and then at first SLOWLY drive away until the engine comes up to operating temperature before normal accelerations and speeds are used. The loaded engine will heat up the oil much faster, putting much less water in the oil so that less time will be required to release it once the oil is at operating temperature. Still, a drive of less than 30 minutes duration will not allow the oil to release all of the water its emulsifier has tied up. If damage has already been done by too much idling and too many short trips causing the emulsifier to separate from the oil, it cannot be reversed, and again the oil MUST BE CHANGED IMMEDIATELY.

Additionally, if previously separated additive goop is not removed from the engine when the oil is drained (and it probably cannot be), the new oil charge is immediately compromised due to its emulsifier being used up trying to absorb the water in the goop left behind. Several back to back oil changes (at 500 to 1,000 miles) may be required to normalize the situation. There simply should NEVER be any "goop" or corrosion evident in a properly maintained engine!!

As to why would BMWNA and their service managers say that there is not a problem??? Well, they are actually correct in that the engine doesnt have an engineering problem. BUT where they fail the Customer is in not advising the Customer that their vehicle is being subjected to SEVERE service and does have a maintenance problem which will require more frequent oil changes. But Im giving them the benefit of a doubt as I really dont actually believe they understand the problem, and what they dont technically understand or have just come to accept, they dont want to admit to least they might have to deal with it. They take the arrogant attitude that the Customer is ignorant (stupid??) and will just accept what they say regardless of how ignorant (stupid??) their (BMWNA & S/M) position may be.

For what its worth, to the other extreme, driving through a sand storm at 120 mph in 110 degree ambient temperatures would also be considered SEVERE SERVICE (and a severe attempt at suicide). The best service a vehicle will experience is interstate mileage at a constant throttle setting on a 72 degree day with only the driver on board.

 Sorry it's a bit long.

Regards Jim