Thoughts on oil change intervals (time, not mileage)

One thing I should have mentioned is that I'm in San Diego. We don't exactly have "winters" and the RV is used all year.

Mike,

Summary: My educated guess - Go with the 5000, but don't go too much longer than a year.

Being in a similar situation, I discussed this very issue with an engineer friend at Exxon/Mobil some years back. I was most curious because at the introduction, Mobil was saying that passcar applications could run 25K miles and at 25K or one year, the oil filter should be replaced and the lube oil brought back to level.

He remarked on my good memory and said that they had to revise this because of the accumulation of moisture and combustion by-products in the lube oil that caused corrosion.

Remember that Mobil 1 was introduced many years ago. Engines run much cleaner now than they did then. I expect that the combustion by-products are cleaner and there is much less of them with the advent of round cylinder bores and other such things.

So, if you don't get to 5000 in a calendar year, just don't go too much past that. I would not let it go through two winters.

Matt

This is pretty much my thinking. Any moisture and volatiles will boil off since the engine is run at operating temperature for extended periods of time even though the total mileage ends up being relatively low.

I've put 40,000 miles on in six years but recently I haven't been racking up the miles quite like before.

I agree that an oil analysis is the only way to know for sure.

Mike

DrewE wrote:
In your (Mike Schriber's) case, I hardly think it matters too much because you're never going to approach wearing out the engine at that pace. It's up there with concerns about rotating the tires on most motorhome when said tires are going to need replacement due to age rather than treadwear.

I think the main concern for the age limit is that putting few miles on the vehicle is usually associated with short trips where the engine doesn't get up to temperature and so many contaminants that would otherwise boil off just accumulate. That's not really the case for you (or most motorhomes, really), so the time limit is probably not very important. Oil itself doesn't have a particular shelf life after which it goes bad or sours or something, at least not in the timeframes we're talking about.

Read the article in the link below. It speaks of a never change the oil engine in a lawn mower. Mowers have no oil filters, operate in dusty conditions and are air cooled which means cooling may not be optimal. The way Briggs does this is by using automotive style engine parts and tolerances. So much for this factory feeling that acid builds up over time or the oil wears out. I don't know what they think of regarding dirt in the oil.

http://archive.jsonline.com/business/new-briggs--stratton-lawn-mower-engine-never-needs-an-oil-change-b99433283z1-290423731.html

Our 2008 E-450's maintenance schedule calls for every 7,500 miles or every 6 months. We put about 4,000 - 5,000 miles on it per year. Sometimes more, not usually less (except when gas was $4/gal). I change the oil every April using Mobil 1 full synthetic and a Motorcraft Oil Filter.

Seems senseless to change the oil after only a few thousand miles.

-Michael

Yep, I too use process of analyzation,....I analyze it by eyeball,...when I
don't like the looks of it, I change it ! :)

CJW8 wrote:
You can have it analyzed at one year and the analysis will tell you if you need to change it.

This is the only correct answer. Anything else is speculation and anecdotal evidence. If you would rather not bother with sending oil for analysis, the safe bet is to change your oil in accordance with the manufacturer's service schedule.

Not a petroleum engineer, don't play one on tv. I've been using the Motorcraft 5w/20 since new with Schaeffer lubes additive and changing every 3-5k miles wthout fail. Oil changes are cheap insurance. I run the dog pee out of this engine to pull my 8k lbs trailer, and it has never used ANY oil between changes, doesn't smoke and loves to rev. 145K as my daily driver and tow vehicle for 10 trips a season. Im not worried about oil so much, but I found out the hard way coolant can be very expensive if not changed under the extreme duty schedule. Very!

In your (Mike Schriber's) case, I hardly think it matters too much because you're never going to approach wearing out the engine at that pace. It's up there with concerns about rotating the tires on most motorhome when said tires are going to need replacement due to age rather than treadwear.

I think the main concern for the age limit is that putting few miles on the vehicle is usually associated with short trips where the engine doesn't get up to temperature and so many contaminants that would otherwise boil off just accumulate. That's not really the case for you (or most motorhomes, really), so the time limit is probably not very important. Oil itself doesn't have a particular shelf life after which it goes bad or sours or something, at least not in the timeframes we're talking about.

You can have it analyzed at one year and the analysis will tell you if you need to change it.