Three Very Specific Questions RE: Synthetic Oil

[SeaKaye12]

(1) Can the use of Synthetic Oil have any affect good or bad on the results of a smog test?

(2) Does Synthetic Oil tend to get consumed at a faster rate than conventional oil?

(3) Compared to using conventional oils; Does the use of synthetic oil cause sparks plugs to foul less in an engine that is burning oil?

I have a Ford F-150 4.6L that "uses" oil at a rate of a quart per 700 miles. When I bought it; the PO had Mobil 1 in there; and claimed that it didn't use "a drop" of oil. There are no leaks (none!) and when I changed the plugs the old ones looked fine. It passes California smog at the top of it's class. I'm wondering where the heck all the oil is going.


I'd be tempted to switch back to conventional oil; but I don't want to start fouling plugs and failing smog tests...hence the questions.

Thanks, Chuck

 

[xtraham]

Re: Three Very Specific Questions RE: Synthetic Oil

I would say that synthetic oil could help with a smog test on an engine that's using oil because synthetic oil does not burn or smoke.
It will also help the plugs last in an engine using oil for the same reason.

a quart every 700 miles with no leaks is more than likely the valve stem seals or possibly the PCV system. If you switch back to dino oil be prepared to see some smoke on restart after it's been sitting.

 

[rwise]

Re: Three Very Specific Questions RE: Synthetic Oil

If it is using oil it will use more synthetic than dino

I have had the seals start leaking right after changing from one to the other

also if its the valves there use to be a seal set that you could get that covers the valve guide and stops the problem and can be put on without pulling the heads.

 

[haskindm]

Re: Three Very Specific Questions RE: Synthetic Oil

Unfortunately, most manufacturers consider burning a quart of oil every 800 miles or so as "normal" Synthetic oil should have no effect on emissions testing. A vehicle that is using oil should use a nearly equal amount of synthetic or conventional oil.
Switching to synthetic oil will not cause leaks, however if an engine is leaking oil, it will usually leak more synthetic oil than conventional oil. The leak was not caused by the synthetic oil, but since synthetic oil is "more slippery" than conventional oil more will leak out.
Different brands of oil have different types and amounts of "seal swellers" in their additive packages. If you switch from a brand with one kind or amount of seal sweller to another, leaks may get worse or show up. That is the main difference in the oils specified as being for high mileage vehicles - they have a higher concentration of seal sweller. Have you changed to a different viscosity of oil from that used by the PO? Is there a puff of smoke upon startup, or a fine sandy deposit on the spark plugs? If so, I would suspect that your valve stem oil seals are leaking.

 

[Howard Sterndrive]

Re: Three Very Specific Questions RE: Synthetic Oil

synthetic oil does not burn or smoke.

It certainly burns. I don't know if it smokes as much or not.

 

[LubeDude]

Re: Three Very Specific Questions RE: Synthetic Oil

but since synthetic oil is "more slippery" than conventional oil

This is a misnommer, or a false statement or whatever!

All molecules are the same size so it creates less resistance and friction. OK, I guess that makes in "More slippery"!

If you have a leak it will be worse with synthetic.
synthetic is normally thinner, It may be the same weight but it is physically thinner also. Synthetic oils are what I call "Creapier" Than conventional oils, I swear that synthetic oil can crawl out of a bottle just setting there on the shelf!

 

[windsors03cobra]

Re: Three Very Specific Questions RE: Synthetic Oil

I do not know if synthetic smokes or not, surely it burns I am surprised that truck is not smoking blue waves from the tailpipe.

Bad valve stem seals, pretty common for early 4.6's. Usually higher mileage engines but not always.
Can change in place with compressed air in the jugs and

http://www.thetoolwarehouse.net/shop/OTC-7928.html