How come gas vehicle engines don't burn oil?

[not2old]

The thread title is funny
Back in '74 I had a 1966 Dodge Valiant slant 6 (bought in 73 for $100) that I drove from Vt to Ca and back in '74. When I started out I was getting almost 200 miles/quart. By the time I got back about 6 months later I was only getting 40 miles/quart.
Some gas engines do burn oil!

This reminds me of my brother's first car. He bought it for $1.00 and I think he got taken. A 1959 Morris Oxford stationwagon that he drove for awhile before selling to a friend. The friend's first trip was from Vancouver to Kelowna, a six or seven hour trip. He took a 5 gallon jug of oil with him and had to buy more for the trip home.

 

[buck12]

The only vehicle that we have owned that used oil was a 2000 Nissan Maxima. At about 75,000 miles it started using oil like crazy. No leaks and no smoke but it consumed oil like crazy. That is the only foreign car we have owned and will likely be the last.

 

[zzvyb6]

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.

Oil regulations again because of emissions, also help get rid of oil that was not oil. That's why many engines died. Those who changed their own oil with high priced quarts got long life.

And: No no no, The oil consumption issue was addressed by the Clean Air Act and it's successors. Today, ONE mis-fire in the entire Emissions City, LA Schedule and City schedule causes the vehicle to fail the test and not allowed for sale. They collect all the exhaust gas in a bag and count the number of carbon molecules just to make sure. carbon atoms are bad. high temperatures in the motor are bad, so less burning. Compression ratios are down to reduce nitrogen oxide. And, just to make sure, some of your precious gasoline is bypassed from the intake to pass it down stream to heat the catalytic converter. This ensures passage (usually). The tradeoff is fuel economy rating.

You probably don't know this, but now days many off-continent cars sold here are qualified for emission by using higher octane indoline (not gasoline. Inodline Clear). Then of course they put cheap gas in the car and then they don't pass emissions sniffers. And they don't get the sticker claimed mileage, either.

BTW: in most cases, a new car's operation actually cleans up the smoggy air in the polluted cities. Air out is cleaner than air in. Once again (1 Misfire). Take the tour of the EPA's emission lab in Ann Arbor. I'm just north of there. Quite a show. The bag full of jelly beans, all colored but 1, represents the allowed combustion engine emission content.

I worked for an auto company and lived just down Plymouth road from the EPA. I knew the process pretty well.

 

[Frankenkubota]

I think it was Honda that sold a gas powered low emissions vehicle in cali, maybe in the 90s. I was out there reading the local newspaper that had an article about a guy who tried to commit suicide. He put his honda in the garage, started the car, shut the garage door and climbed into the car for his final voyage.

He woke up in the morning, car ran outta gas. Article said air in garage was cleaner than outside air.

 

[kenmac]

I would like to know which brands don't use oil between changes cause the last two I have owned sure did..
I still own the Hyundai

 

[LouNY]

I will say that my RAM 1500 with the eco-diesel engine uses very little oil.
I have never gone the 10,000 miles between changes usually between 5-6000 miles between changes afew times it has been a half a quart low when I changed it and one time I did add a quart a few weeks before I got it changed, a bit over 90,000 on her now.

 

[deezler]

Dyno lab mech engineer here. We run a lot of oil consumption tests.

All engines burn some oil. No set of piston rings is able to scrape 100% of the oil of the cylinder walls on the downstroke. You wouldn't really want that, anyway. Then how would the rings be well lubricated for the return upstroke? Oil consumption is a known engine design consideration. Most OEs target around 10,000 miles per quart nowadays.

So why don't you notice that on the dipstick? Well, either you're not paying real close attention, most likely, and it's still in the "normal range" on the stick. No problem. More likely, some of the oil that has been burned away has been replaced in volume with combustion byproducts (soot and un-burned or partially burned hydrocarbons), and especially in direct-injected turbocharged engines, raw gasoline. It sneaks past the rings down into the crankcase from cylinder pressure, or gets scraped down if left on the cylinder walls during the power stroke. We call this "fuel dilution", and it can get as high as ~10%. Meaning, 10% of the oil you drain out during a change is actually mixed-in gasoline. Diesel engines do this also.

All engines burn oil. They have to. If you don't notice it, or it seems like zero consumption, great!

 

[kenmac]

I do 10k oil changes. My Hyundai will consume 2 qts of oil during that time

 

[buck12]

I would like to know which brands don't use oil between changes cause the last two I have owned sure did..
I still own the Hyundai

I current own four Fords. The oldest being a 1993 F150 up to a 2016. None of them have shown low of oil on the dipstick.

 

[Molalla1]

And back in the olden days. If you only burned one quart per thousand in a brand new car you were lucky.

Yep and non detergent oil you let the crude build up.