Oil for a '97 Northstar - Is there a verdict?

[BostonETC97]

Hello!

I'm curious if there was ever a final verdict on the preferred motor oils for the pre-roller N* engines. I've been running mine just as the book says - 10W-30 conventional oil, changed when the OLM says so. I've got close to 105k on the clock, and she still runs like new. No oil leaks, frequent WOTs, and I add a quart every 1500 miles to keep the oil level centered on the dipstick.

I should mention, I have NOT been using rotella, EOS, or any supplements. I run straight 10W-30, with the starburst label, and newest (SM?) rating. My mechanic likes Castrol GTX for the oil changes, so I usually buy a case of that every year, just for the occasional top off.

I've been trying to follow all the posts and articles about the reduced zinc content, but even as a pre-med student with research experience, I still can't figure out what the overall 'verdict' really is!

Since my intentions are to keep this car for as long as it'll reliably run, I'd be happy to use whatever oil is deemed the most 'safe' to use in this application. Will my cam-lobes disappear if I continue my current oil regiment?

As always, I appreciate the input - there's some great knowledge and brilliant people on this board!

-Scott

[kev2]

No need for additives, GTX is a very good oil I would stay with that, BUT pay more attention to the MILAGE between changes sometime the monitor will stretch the milage unreasonable.

When and IF GM writes a TSB concerning zinc in oil BE sure it will appear here ....and the debate will go full bore.

[BostonETC97]

That's what I was hoping to hear! My OLM tends to change the oil at approx 3-4000 miles. My driving is 80% local city (suburban) driving, with the remainder being highway. I check the oil every time I fill the fuel tank and have found that I usually add only one or two quarts at most between oilchanges. I always use the ac-delco oil and air filters, and even at 0% oil life, the oil is always a rich dark brown, never black or burnt.

I was never bothered by the small oil consumption, as I like the piece of mind given by adding a fresh quart to the engine. I usually keep a quart of oil in my trunk, just incase I'm not close to home when I need it. I don't baby the car, and make it a habit to go WOT atleast once a week. This seems to be working well, as there's very little oil consumption, and no black smoke behind me. Idle is silky smooth, and there's no hesitations or stubling of the engine.

I was beginning to get anxious with all the talk of reduced ZDDP, but I'm glad to hear that I'll be ok with regular changing of the GTX oil!

It seems as long as the headgaskets don't grenade, and the oil doesn't eat my engine alive, I can probably get another 100k miles out of this car!

[JimD]

There is not a more subjective discussion than oil recommendations for the '99 and earlier Northstar engine.

And discussion is all it can be at this point since there has not been a post here, or on other Cadillac boards that I visit, regarding bearing failure, or camshaft surface failure, that can be linked to using SM oils in an engine that was designed/built when SL was the state-of-the-art oil rating.

Granted; vehicle-specific "problem boards" like this one are a very small sample of all Cadillac users. But, this is the data we have access to; GM design folks have an advantage in this regard.

For 164,xxx miles I have been running the OLM down to 0% and using the least expensive off-the-shelf Starburst oil in my '98 engine. Will my engine crater next week due to bearing failure? I doubt it.

Will my engine still be humming along the Interstate at 264,xxx miles? Stay tuned for the answer to that one.