What factor hits oil life expectancy the hardest?

[martyi]

First, I'm not asking the question as it relates to off-road applications, race cars, etc. Rather, what factor do you think adversly impacts on oil the most for every day drivers in their family car?

I know these factors would probably fall under "severe" conditions such as short trips; cold start; dusty and hot environment, etc. But what single factor, condition or driving habit do you think hurts your oil's ability to do its job?

 

[Dagwood]

I would imagine high RPM and hard driving might challenge an oil's life expectency. Cold starts and high RPM before the car has warmed up would be my vote.

 

[Pablo]

Cold start and incomplete oil heating with resultant unevaporated condensate (

water and some fuel) remaining in oil seems to be the worst thing in general.

 

[racer12306]

in our race car the issue was alky washdown. we didnt catch it until the end of the season when we tore the motor down and found that the bearings had been eaten up by the alky. when we get to racing it again my dad said that we will use conventional cheap stuff and change the oil after every time we race. alky washdown is the biggest issue in our case.

yes only real way to know is to do a uoa and then determine how many runs are on that oil and change it that many runs every time. most of the time drag runs are pretty consistant as far as abuse to oil in my opinion because you go to the shift point the same amount of times every run and you are on the throttle that same amount of time every run assuming it is a normal pass.

 

[Raven18940]

Short trips are the worse I think. To contrast, I drive my car really hard (lots of revs, full boost, some idling, and no highway miles), but I drive it a solid 40 minutes at one time twice a day. I just did a UOA at 4000 miles and it's still a thick 40 weight with a TBN of 3.7 and single digit iron numbers.

 

[widman]

Short trips without fully heating the engine are the worst for most people because of the moisture (and sometimes unburned fuel) that remains. Here our real limitation is dirt contamination, as there are always high winds and dust.

 

[glennc]

Yes, I'd agree, short trips, lots of cold starts, and also lots of idling. Those will use oil up in a hurry. These the conditions that use up the additives in the oil, bring down base number, and result in contamination.

High-rpm running might cut oil life, but mainly through shearing to reduced viscosity - and that depends more on the particular oil, VIIs and so forth, and in any case is IMO much less destructive to the oil than the former.

- Glenn

 

[GenesToy]

I believe a engine that never gets up to temp to burn off the excess fuel washing past the rings. A cold running engine possibly with a stuck open thermostat in cold weather. A poor running engine is hard on oil also IMO leaves a lot of unburned fuel in the cylinders.

 

[ruking77]

http://www.chevyavalanchefanclub.com/fun_stuff/may2002/page002.html

Given important variables,OLM's tell the story. Oil analysis is the true nitty gritty. In addtion as most folks know, the oil analysis main purpose is to be used to indicate engine TRENDS. I think the real cutting edge in terms of issues is whether or not the OLM's are close to the (actual) oil analysis and vice versa for the puposes of normal "useful" oil life remaining.

[ December 04, 2005, 03:22 PM: Message edited by: ruking77 ]

 

[bruce381]

From Pablo:

"Cold start and incomplete oil heating with resultant unevaporated condensate ( water and some fuel) remaining in oil seems to be the worst thing in general"

I agree and then high heat will kill it also.
bruce

 

[ARB1977]

Not changing it when your supposed too. The more abuse the more often you need to change.

 

[TCP442]

I would say cold starts that end up in short trips especially in cold weather will kill an oils lifespan significantly

 

[toneloc12345]

Why is idling so bad for your oil? My work is only about 15 minutes from my house. In the winter should I let my truck warm up for 5 mins, or just get in and go?

 

[Patman]

GM's OLM counts down faster if you rev the engine higher, and it counts down faster when the engine temperature is colder, so those two factors are what GM considers to be the biggest detriment to an oil's life.

 

[Patman]

toneloc, you'd be better off spending those extra 5 minutes driving the truck a little bit further distance, than you would in idling it 5 min. Driving it for those extra five minutes will help get the oil temperature hotter. Idling an engine will not raise it's oil temperature very fast at all.

 

[vad]

quote:

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GM's OLM counts down faster if you rev the engine higher, and it counts down faster when the engine temperature is colder, so those two factors are what GM considers to be the biggest detriment to an oil's life.

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Those two factors being the biggest detriment?

Would you please provide the sources supporting that statement.

 

[ruking77]

..."The patented engine oil change technology involves computerized monitoring of engine revolutions, operating temperature, and other factors to optimize the change interval selection" ...

You might want to read the article, the link is given in my post.

 

[rg144]

But 'computerized monitoring of engine revolutions' and counting down faster are two different statements. Highway miles are easier on oil, for example. Presumably those miles (at high RPMs) would not count down faster on the OLM.

So good question, what does the OLM algorithm treat as first 2 determinents? Probably temp and time in low temps.

 

[glennc]

The BMW service indicator system in my E30/E32/E34 uses coolant temperature, rpm and possibly one other parameter that I can't quite recall at the moment. If I do recall correctly, it weights low coolant temperature most heavily.

In later iterations of the service indicator system BMW simplified the algorithm.

- Glenn

 

[vad]

quote:

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But 'computerized monitoring of engine revolutions' and counting down faster are two different statements.

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Second that.