Oil recommendations for a 120k mile LM1 V8?

[9C1_guy]

Hi -- New to the board, found it through another web site. I have a 1987 9C1 Caprice, which is an old police car. I'm looking for recommendations on oil, given the age of the car. Per the sticky, here's the info about the car:

1. What kind of vehicle you have

1987 Caprice with a 5.7L/350 cu. in. LM1 V8 engine and 120,000 miles.

2. What your owner's manual says -- not just viscosity, but certifications (look for acronyms like API SM, ILSAC GF-4, etc.) and change intervals as well

I don't have the owner's manual (I'm buying one from eBay), but the recommended viscosity is 5w30, per the oil cap in the engine. Recommended change interval is (I think) every 3k miles.

3. Where you live

Northern California.

4. How you drive (easy? hard? fast? slow?)

I don't do hard accelerations or stops. I drive about ~70-75 on the freeway. Mostly "average" around town. I haven't received any sort of moving violation in well over 10 years, if that's any indication.

5. What your daily drive is like (short trips? long trips? city? highway?)

Daily drive is a minimum of 10 miles, one way and a maximum of 25 miles one way. 20% city streets, 80% highway.

6. Whether your car has any known problems

It burns one quart of oil every 1000 - 1500 miles. No leaks of any kind (garage floor is clean). An occasional squeak or rattle, but no other mechanical problems.


I don't have any strong preferences on kinds of oil. I'll gladly pay a premium for a higher quality oil, but don't want to pay a premium just for a brand name.

Given how well the car runs, I'd like to do what I can to extend the life of the engine before ultimately needing to rebuild it, so looking for recommendations on the best oil to accomplish this goal.

Let me know if any other info would be helpful. Otherwise, thanks a ton for any suggestions or recommendations.

--kurt

 

[Rhymingmechanic]

Do you have a carburetor or fuel injection? If it has a carb, I would suggest changing under 5000 with a conventional or high-mileage 10w30, or maybe high-mileage 5w30 if you see cold temps often. Change instead of adding a second or third quart of makeup oil. The small-block had roller lifters by then, so antiwear additive for the lifters isn't a concern. Any current conventional oil will be better than what was speced in 1987. Synthetic would probably be a waste of money considering the engine's condition and your driving style.

I had an '87 Caprice police car, too, and ran 10w30 Castrol syn blend, adding a quart at 1500 and changing at 3000. I'm pretty sure the previous owner used Pennzoil 10w30. That was pre-BITOG, and I used the blend because I figured it was "better" than regular oil. The Caprice had an oil-air cooler and was the newest used car I had ever owned at the time, so I extended the mileage from the 2000 mile interval I was using on a slant-six Duster.

 

[9C1_guy]

It's a carbureted car and thanks a ton for the suggestions. I've also read other posts on here where folks seem to really like auto-rx. Is that worth looking at given my particulars?

 

[dparm]

If you got to 120k, I think you can keep doing what you're doing!

 

[Rhymingmechanic]

Originally Posted By: 9C1_guy
It's a carbureted car and thanks a ton for the suggestions. I've also read other posts on here where folks seem to really like auto-rx. Is that worth looking at given my particulars?



That's a can of worms right there. Ask about ARx in the additives forum and you'll get the whole spectrum of answers, and could end up with a crankcase full of who-knows-what if you're not careful. If you don't have leaks or lots of crud or sludge, you might not notice anything from using an additive. Your oil consumption is probably normal for that engine and mileage, and if you don't have leaks now, consider steering clear of anything that could make 24 year-old seals and gaskets begin leaking.

My experience with Auto-Rx--it didn't change oil consumption in a worn-out Saturn, but I didn't really expect it to because oil burning was basically a design feature of that engine. The filters caught some nasty-looking grit during the process. It did stop a manual transaxle leak in the same car.

What oil are you using now, or did you just get this car? Since it has a carb (more fuel dilution than injection), dino or Maxlife at a conservative mileage interval would probably serve you well. Change the PCV valve with an AC Delco if you haven't recently.

Be sure to give your transmission some attention as well. Mine had a late revision of the 700R4, which was not known for durability. I put in a shift kit and added a cooler & drain plug, and the trans took me from 150,000 to 205,000. If I had known about them, I would have installed a Magnefine inline filter, too.

 

[Merkava_4]

I'd be tempted to run 10W-40 MaxLife in that old Police car.