15W40 + lucas stabilizer to fix oil burn

Messages
3
Location
Washington
I have a 1998 subaru legacy outback with 180,000 miles. Much to my dismay this car has been burning a lot of oil... almost one quart every 1000 miles. I was previously using 5W30; after doing some research I read that using a thicker oil could possibly help reduce oil burn (slipping past the pistons). I was also recommended Lucas Oil Stabilizer at my local auto shop. On this last oil change I used 3.5 qts of Rotella 15W40 and 1 qt of lucas oil stabilizer. So far the car has been running great - the check engine light has turned off, and I haven't lost any oil! The car starts up just fine (it MIGHT be slightly slower to start on cold mornings but hardly noticeable). After doing some more reading I have concerns that perhaps I could have been a bit over-zealous with the "thick" idea and the oil I have used plus the Lucas Oil Stabilizer may be too viscous. I am on the west coast and the temperature is not going to be below 45 degrees F (high temperature right now is around 70). Any thoughts? Thanks!
 
Messages
6,614
Location
southeast US
15W40 is not too thick in your climate, at least during summers. Subaru allows up to 20W50 in heavy duty driving. See your owner's manual. The only negative is decreased MPG. I used 5W40 in my Subaru due to towing over the limit and got lousy city MPG of only 18 on short trips.
 
Messages
28,123
Location
Regina, Saskatchewan, Canada
Friendly_jacek makes a good point. If you're OCIs aren't too short, a 5w-40 is certainly an option to consider as a year round oil, assuming it performs as well as the 15w-40 from a consumption standpoint. I'm not a fan of most oil additives, particularly Lucas. The 15w-40 isn't necessarily ideal, but if it's cutting your consumption, it's certainly worth it, if you ask me. Your weather certainly allows it. You said the check engine light had turned off. Did it throw any codes? Why was it on in the first place? Consumption fouling something along the way?
 
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8,136
Location
Mahzurrah!
Forget the Lucas. All you need is a heavier oil if you want to slow consumption. I'd suggest you try a thick 10w40 or even a HM 10w30, they should slow consumption without smothering your engine with overly thick lube.
 

PJFREDDY

Thread starter
Messages
3
Location
Washington
I don't remember the specific code but it was one of those generic air/fuel mix codes. The person at the auto shop told me to tighten my gas cap (which wasn't the problem). Soon after I added the thicker oil the light came off... I was wondering if it could have had something to do with improved compression. It could have been a coincidence of course but I'm happy either way without it. Thanks for the post!
 
Messages
19,479
Location
Chicago Area
We can't complain about the oil being too thick if it obviously solved a big problem. The Lucas additive is an extra expense, and I'd simply use a thicker oil to simulate it. I'd try the 15-40 as is, even if it burned some oil
 
Messages
6,388
Location
Washington St.
Look in the oil additive section for information on Kreen. It can clean carbon from the ring grooves and allow them to seal as best they're able given the wear. It is more likely that the rings are stuck than that they are extremely worn. Don't buy the Lucas stuff. It is a waste of money. You don't need to "stabilize" oil.
 

JGW

Messages
223
Location
New York
"15W40 and 1 qt of lucas oil stabilizer" Might as well use gear oil. Try Mos2, I use it every so often and it seems to cut down on oil consumption.
 
Messages
3,492
Location
NJ, USA
Originally Posted By: JGW
Might as well use gear oil.
Um, no. While the Lucas may not be proper engine oil, the Rotella is. The Rotella has additives in concentration suitable for HDD use, so even diluted with the Lucas it should still be usable as an extremely thick engine oil if a [censored] one of dollar store quality and nothing to panic over. Gear oil would be more in the "drain it now" category. Maybe using gear oil instead of the Lucas to get the viscosity up might make sense, but why not just buy oil that's thicker right out of the bottle instead?
 
Messages
1,841
Location
.
I was thinking what Ken is thinking. That is stuck rings. Horizontally opposed engines are more susceptible to stuck rings. At least that was the thought about 911's. I had two 911's one a 1972 and the other a 1986. Both had stuck ring issues that Kreen fixed.
 
Messages
28,123
Location
Regina, Saskatchewan, Canada
Originally Posted By: PJFREDDY
The person at the auto shop told me to tighten my gas cap (which wasn't the problem). Soon after I added the thicker oil the light came off...
It could have been the gas cap. The code won't disappear immediately after properly tightening the gas cap.
 
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