Well, my 85 Deville is finally running quite well, but now I've noticed that I'm burning about a quart every 500 miles (no leaks at all). There's never any blue smoke out of the tailpipe, so it's not too bad.
I don't have the tools to run a compression check, but I'm guessing I probably have a few with low compression. Although, the car always starts quickly and easily and idles very smoothly.
I was wondering if I should try some Restore lubricant or one of those oil supplements, and wanted to know if anyone had tried them. I have NEVER put one in a car before, and am not a supporter of mousemilk additives, but if it helps, it helps.
Generally, lubricant supplements like Restore won't do any harm, at least not short term harm. Most of the time they're nothing more than mega doses of additives that are already in your oil. II wouldn't recommend them for any Cadillac engine - choosing a good oil to begin with is the most important thing.
If I recall, your DeVille has pretty low miles. It shouldn't be burning oil yet. Plus, burning a quart every 500 miles should produce siginificant blue smoke. That leaves only a leak as the source. Next question, is it internal or external? If internal it would be contaminating the coolant, which would suggest a head or intake gasket. If external, it could be a small enough leak that only weeps when the engine is warm and oil pressure is high. Raise the car and check for wet spots or streaks on or near the oil pan, or on the floorboards behind the engine compartment. Also closely inspect the oil cooler lines running from the filter to the radiator. They are sealed on both ends with O rings that do wear out frequently.
I'll check for that. As I said, the car runs very nicely now (definitely has all 125hp--surprisingly peppy), and I've never seen any smoke.
I don't think a gasket is blown as my oil looks normal and my coolant level hasn't moved in over a month of driving since I changed the coolant and refilled it. There aren't any air bubbles in the reservoir either when I blip the throttle.
I think noahsdad is right--probably a leak in a place where I can't see it. Very strange. The oil pan gasket and rear main were bone dry last time I was under it. I'll keep a look out.
I've decided against putting Restore or any other lubricant in it. I'll just keep topping it off with Rotella.
See now, if you drove a Jaguar or Rover you'd be worried if it didn't leak oil! Glad to hear your 85 is back in shape again. I agree about the peppy part. It's not tire-smoking burnout torque, but it gets to 60 plenty fast.
My 87 has a leak that has confounded me for three years. It's not major, it doesn't even require topping between changes, but there are 500 drips on my garage floor. The bottom end is dry as the desert, the cooler lines are clean, and the valve covers are spotless. I fixed it by buying a little piece of plywood for it to drip on.
Because of the age and extremely low mileage, my first guess would be that the oil control rings are crudded up. Back in the day a product called Engine Tune-Up from Wynns used to work wonders on sticky valve lifters. Might be worth a shot.
Automobile(s): Cadillac 78 Seville, 78 Coupe de Ville, 92 Sedan de Ville
Re: Restore Lubricants
Is there any oil film under your floorboards or on the rear bumper? I had a leak in my oil pan once that only leaked while it was running and missed the exhaust so I couldn't smell it, but the rear bumper gave it away.
No, no oil at all under my floorboards--and no drips! I just checked under the car and there's nothing at all!
Slight update: I recently bought the GM dealer's remaining stock of top end cleaner (5 bottles) since it has been discontinued and I own 3 cars with throttle body injection. I dumped another bottle down the TBI the other day and followed the procedure again. I guess it's supposed to help recondition valve seals and oil rings too (at least according to the bottle).
I've driven the car about 300 miles in the past few days and my oil level hasn't gone down at all--and I've been parking in the same spot every time to check it. Very strange. My guess is that one of my cylinders had some blow by. My oil used to start discoloring after about 300 miles (just to a darker brown--reminded me of when I had a diesel car), but I rechanged it after I used the top end cleaner, and it still looks as good as new 300 miles later.
The car has a good amount of power now and seems to come on strong after pushing down about 1/2 way on the accelerator, at which point it really "takes off" (Ok, I know it's a 4.1, but it really isn't bad on power). It's almost like it has a turbocharger. Anyone else have experience this? I remember my 91 CDV with the 4.9 used to do the same thing. Very tame until 1/2 way down, at which point, if you pushed further, it just flew down the road and emitted a loud roar.
Automobile(s): 1991 Sedan deVille 4.9L/1994 Lincoln Town Car 4.6L
Chatham, Ont., Canada
Re: Restore Lubricants
If you have no drips apparent, you are certainly burning it or losing it into your coolant. You can burn quite a bit of oil and not see smoke from your exhaust. My dad's Town Car is an example. Apart from a complete engine rebuild, a compression test will tell you if it is worn rings, or bad valve seals. Intake gaskets also can leak, and the oil will fly off while driving, but not leak while sitting. You can check that by seeing if there's any oil pooling below your intake.