How come gas vehicle engines don't burn oil?

[sixdogs]

If gas engines need oil on the cylinder walls to lubricate, why doesn't residual oil get burned off and in time show up as a loss on the dipstick? Seems like it should.

I can run my newer gas truck for 6,000 miles and when I check just before I change it, the oil level is the same as when I first changed it 6,000 miles earlier. I don't get it. Shouldn't some have been burned off?

 

[Jstpssng]

THe rings wipe the cylinder walls on the downstroke. Often as an engine gets older and the rings/cylinder walls wear, you will indeed start using oil.

 

[MoKelly]

I agree with you - there should be some oil loss after 6000 miles. On my Honda, the owners manual says a loss of oil up to 1/2 quart between oil changes is considered “normal”.

MoKelly

 

[jaxs]

THe rings wipe the cylinder walls on the downstroke. Often as an engine gets older and the rings/cylinder walls wear, you will indeed start using oil.

That's exactly right. If it's bothering you sixdogs you can make it start using oil by driving around the block a few time between draining and refilling oil next time you change oil.

 

[not2old]

My 1990 F250 used one litre of oil between changes every 6000 km. when new. At over 30 years old and 438,000 km it now uses two litres between changes. When new, I thought it was a bit much but time has proved it wan't a problem as it has yet to require any engine repairs.

 

[ruffdog]

That's exactly right. If it's bothering you sixdogs you can make it start using oil by driving around the block a few time between draining and refilling oil next time you change oil.

.....or just start burning 2-stroke premix if you want....?:confused3:

 

[Molalla1]

THe rings wipe the cylinder walls on the downstroke. Often as an engine gets older and the rings/cylinder walls wear, you will indeed start using oil.

Yep, agree that is it ^^^

 

[ruffdog]

We have better machining practices, materials, coatings, and lubricant now so they burn cleaner.

 

[jaxs]

We have better machining practices, materials, coatings, and lubricant now so they burn cleaner.

We sure have. 100,000 miles used to be about all you could expect before rebuild. Used car dealers used to buy "skeeter foggers",put a heavy cross hatch on cylinder walls and install soft rings that would rapidly wear and "seat" then run real fine,,,,,,,for a few thousand miles. Pork skin and shoe leather under crankshaft bearings? I wouldn't know anything about that.

 

[rademamj1]

Used to be engine oil losses were common, but when the Japanese cars hit the American markets and were quite successful in sales based on their high reliability, nearly all automotive manufacturers around the world tightened up their machining standards, and so tolerance gaps between piston rings and wall are now so close, no oil is burned. Now it's not uncommon to see Toyota cars going 500,000 miles these days, and lots of American made cars can also do those longevity miles. Back in the 60's any car getting 100k miles, was ready for an engine rebuild or the junkyard.