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Re: oil change opinions. every 10,000 mi?! Posted by Ari [Email]  (#2847) [Profile/Gallery]
(more from Ari) on Fri, 11 Oct 2002 11:36:47
In Reply to: oil change opinions. every 10,000 mi?!, Tom, Thu, 10 Oct 2002 21:55:59 Members do not see ads below this line. - Help Keep This Site Online - Signup |
The recommended oil change interval is a marketing decision first, an engineering decision second. A car with 10K oil changes has half as many as a 5K recommendation. That affects the 'cost of ownership' metric that some places use. From a marketing standpoint, it's great to drop that cost of ownership.
The other thing to think about is that with modern oils, and modern engines that spew fewer combustion products into the oil, you just don't get many oil-related failures in the first 100K miles of life. The difference between a 5K oil change and a 10K oil change isn't going to show up at 30K, 60K, or 80K. The oil changes you do at the beginning of engine life show up after 100K. Unless you run the car low on oil all the time, damage is due to wear, and wear takes time.
Back to marketing - set that oil interval such that oil related failures are pushed out past the end of the warrantee period. There is relatively little payback for a manufacturer if the average engine life is 150K or 175K. But the oil changes at 20K affect that.
OK, here's my personal opinion on motor oil. I don't claim any divine knowledge, just my opinion.
Synthetic oil is great for how it maintains viscosity and lubricity over a wide range of temperatures. It will resist breakdown if you drive your car hard, and will provide good lubrication at startup on those really cold days. If I were to race or autocross my car, that high temperature part would be invaluable. If I lived where it regularly goes below zero, I wouldn't be without it.
"Conventional" oil from reputable manufacturers is pretty darn good. It does break down over time, but when it's pretty new, it's pretty close to synthetic in terms of protection. It also costs much less.
The oil system gets water and particles. Yes, most particles get caught by the filter, but not all. Water in the system boils out, but it leaves acids behind. Most of the additives in oil are there to buffer the acid buildup. Once those additives are used up, the oil gets acidic.
This is my approach - since my cars don't see 'extreme' service conditions, I use conventional oil and change it (and the filter) regularly. That's 3K-5K, every 3-4 months. At that interval, even conventional oil is still pretty good, and synthetic would be great. But I'm flushing out the water, acids, and particles. I'm putting in a new filter. It's not the oil I'm worried about, but the crap in the oil.
My issue with longer (10K) oil changes is that the filter doesn't get changed. OK, you can change the filter at 5K, but that seems like a hassle - if you're in there, just do it all. Since I'm doing it frequently, the conventional oil doesn't get a chance to break down. So I save the money.
For things that don't get changed frequently, I use synthetic. I use synthetic in manual trannies. That oil stays around longer, and you can feel the difference in shifting, especially when cold.
There is no question that synthetic will do a better job than conventional. I'm uncomfortable in letting stuff swirl around in the engine for 10K - I want it out sooner. Since I change the oil sooner to get the crud out, I don't think the additional cost of synthentic is worth the marginal improvement (in new oil).
End opinion.
posted by 192.249....
, Fri, 11 Oct 2002 11:36:47 <-- Viewing This Message, Mon, 14 Oct 2002 09:55:53
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