My 2 cents:
With today's modern engines and lubricants, it's unlikely an engine is going to "wear out" during the warranty period regardless of whether the owner follows the factory recommended oil change intervals or has it changed more often. After the warranty is over, the manufacturer wants you to buy a new car.
If you are trying to get 2 or 3 times the warranty life of an engine, then changing the oil more often makes sense. If not, you are wasting your money.
Eisboch
But I don't buy new cars and often run them well beyond any warranty. My last BMW was at approx 150,000 miles when I sold it (E34 525 24 valve) and that was in rude health. The 'specialist' that bought it from my dealer clocked it back to 70,000 so must have thought so too...;-)
My previous one, an E28 520, now belongs to my brother and despite a hard life towing is approaching 250,000 miles. The bodywork will see the end of that car - not the engine. It's still sweet and burns no oil.
IMHO there are very very few people who buy a car new and run it to high miles - apart from business users. And business users are the ones long service intervals are aimed at. If service intervals are marginal you're bound to increase the overall failure rate. Exactly what business users won't tolerate.
You didn't read any of the Toyota stuff, did you? A clear case where overly-long oil-change intervals caused premature engine death. Yeah, we're on a BMW group, but evidence is evidence.
FloydR
I didn't. Your summary was enough. The BMW service indicator takes into account the type of usage and the handbook mentions a timed (not mileage) change for extra low use cars.
I happen to have one of the allegedly sludge-prone Toyota engines, and I've looked into the problem quite a bit. The conclusion that I came to is that Toyota wanted the engine to run hotter for reasons of thermodynamic efficiency, so they narrowed the oil passages. They widened them again on the next generation of engine in the 2002 model. I have never seen a credible report of sludging on an engine that had reasonably frequent oil changes. For a couple of years now, I have been running Mobil 1 out to 7500 miles and getting used oil analyses, and there is no sign of sludging.
As you say, BMWs and Mercs have much higher volume sumps, and hence have the ability to suspend lots more "dirt" than my Toyota. BMW and Merc also specify oils with massive amounts of additives, which gives them the ability to neutralize lots more acid than the cheap stuff.
If I had a BMW (still only dreaming of one!) I would install a fumoto valve (fumotovalve.com) and take an oil sample at 5000 miles, 10000 and
15000 and run analyses on all three, comparing the Total Base Number (which gives you an idea of how much acid neutralizing ability is left) and particulate count (which gives you an idea of how well your filter is performing). These analyses are not very expensive; $40 gets you the lab work plus an expert opinion.Note that there are quite a few people on the bobistheoilguy.com forums that will change their filters halfway through a cycle without changing the oil because they believe the filter is the weakest link.
Changes the oil every 5k in his own Z4 and MiniS.
Yes, that's why we like to maximize the interval.
We take a bath once a year whether we need it or not.
DAS
For direct contact replace nospam with schmetterling
I haven't yet read the Toyota oil thread either, but you did say the ref was to drivers exceeding the recommended interval.
With my 1986 W123 230E (ok, ok, a Merc, but same difference...) I followed the (fixed) recommended intervals and it ran fine for 120 000 miles and 6.5 years till I had to ret rid of it (my company decree). Continued fine service until one of the subsequent owners bent it beyond economic repair.
DAS
For direct contact replace nospam with schmetterling
Dave, do you like banging your head against a wall of finest London brick?
DAS
For direct contact replace nospam with schmetterling
Yup. It's one of my few pleasures. ;-)
And we generally last longer than lardy yanks. Case proven!
Huw
It follows Brits would eat less given they have such a hard time chewing. Anyway recent news has it that ole "fish 'n chips" is turning more than a few Brits into dumplings.
There is some sense to it. Dry nitrogen has (obviuosly) no oxygen or water vapour in it.
Oxygen can attack the rubber, causing some degradation over time. However, this happens to the outside of the tire no matter what you do, so minimizing it on the inside doesn't hurt but probably doesn't help much.
Nitrogen is a slightly bigger molecule than oxygen, so it diffuses through the rubber more slowly. All other things being equal, a nitrogen tire will loose pressure slightly less slowly than an air one. But air is ~78% nitrogen anyway, so that's also not a huge effect.
The biggest one, as far as I know, is change in pressure with temperature. Air contains some amount of water vapour, which apparently changes pressure with temperature more than straight nitrogen (I don't know how the thermodynamics behind that work). In theory, a nitrogen filled tire will maintain pressure more evenly than an air filled one.
I suspect this whole idea got piggy-backed off the airline industry, which does fill their tires with nitrogen. But they do that because, if they use air, the tires will explode under certain situations. No car tire operates that hot, so it's not really applicable.
Tom.
Only if the oil degrades significantly between the change intervals. If your synthetic provide sufficient protection at 10,000 miles, then changing every 8,000 will make absolutely no difference to your engine life.
The engine "wears out" due to loss of metal. That can happen chemically or by metal-to-metal contact. Chemical attack is a function of how well the oil neutralizes contaminants...that does decline with age, but there's a lot of factors that play into that that are more important than just age. Metal-to-metal contact is a binary thing...you either have it or you don't. If you don't, then it doesn't matter if your oil is brand new or 15,000 miles old.
The oil does suspend metal particles that have come off the engine. However, if the filter is working properly, none of the particles in the oil are big enough to damage anything, so who cares?
Tom.
and the small particles that are too small to be captured by the filter, but do discolour the oil, float harmlessly withing the film of oil as they pass through bearings, which is why the colour of the oil is unimportant unless it varies from the norm for that engine at that service interval. Anyone who has ever had and maintained a diesel engine will know this.
Huw
Didn't the 1980s Mini have 3k oil services and the same engine in the Metro have 12k oil services ?
No. BMC petrol engines went to 5k changes in the '50s with the introduction of full flow oil filtration and multi-grade oils.
A diesel's oil gets black within a few hours after changing it. Typically an oil analysis is done from time to time to indicate abnormal wear of the engine. (This is the case of marine diesels, anyway ... I don't know about automobiles).
Eisboch
I didn't know you were English, Huwie... ;;-)))
DAS
For direct contact replace nospam with schmetterling
"Dori A Schmetterling" wrote
There are two obvious problems: 1) Toyota specifies two intervals depending upon the operating regime however it's rarely clear which regime you should categorize yourself into. 2) at least *some* Toyota owners say they changed oil regularly (no proof because who saves all their receipts) and had failures.
I suspect (but of course have no scientific proof - aren't sealed legal settlement agreements wonderful?) that Toyota wouldn't have agreed to an 8-year warranty for specific engines, unless at least *some* such evidence existed.
FloydR
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