I bought my 2008 JK in August with 27k on it. I did my first oil change at 30k switching to Mobil 1 5w30 from whatever the dealer had in her - 5w20 I think - it felt really thin on the fingers. Anyway in about 2400 miles I put 2 additional quarts of Mobil 1 5w30 in as the level dropped. I resigned myself to having an oil burner and began following the threads on that. In the last week I have driven over a 1000 miles, mostly highway. Several 300 mile days for work in the Adirondacks, a little 4 wheel in a muddy clay cow pasture. I finally had a chance to check my oil again this morning - expecting to be down close to a quart. To my surprise the dipstick read full.

After discovering the oil use problem I was planning to switch back to 5w30 dino with maybe a quart of synthetic. I had really good luck with a mix in my '97 TJ (4 banger) and thought it might help. Or at least be cheaper than a quart of Mobil 1 every 1200 miles. I'm due for another change pretty much now. I generally change oil and filter every 3-4000 miles.

I am curious if anyone else has encountered this or has any thoughts on this. I don't think that switching oil types can lead to a burst of consumption and then stop.

 

I have had burning issues (07' w' 70K). But ironically enough, only when I go over 4,000 miles.
Ive ran a few cycles with a syn. blend and that is when I noticed the burn off.

Now I only run full synthetic. (Mobile, Valvoline & Quaker State... whatever is on sale)
but change it every 3k and there is no drop in oil level.

 

Random thought but;

Could your PCV valve be defective, and maybe sometimes sticking open? That might suck oil out of the crankcase, through the intake, into your cylinders. Just pondering reasons why it does not happen all the time. Guess it could also be a piston ring issue, would be interesting to check all the spark plugs.



Based on everything I have read, and a conversations with some mechs I trust, I have concluded that if I still had the 3.8 I would be running 10W-30.

 

Sometimes switching to a higher quality oil brand, especially a syn can expose an otherwise hidden oil leak.

Synthetics in general need fewer viscosity improvers and can have a greater percentage of detergents in their additive package.

What happens is that a good dose of detergents cleans out some sludge build up and may expose an existing "leak".

 

That reminds me of days long gone, my old beater $50 special cars with the 1/4 to 1/2 inch of dirty gunk built up from components seeping oil. Which a wise person did not clean off!