Thinking of switching to Xw40 in Regal

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Aug 27, 2003
As I mentioned in a previous post, my fiancee has a 94 Regal with 120K miles on it. The engine is the 3800 V6. I currently run Mobil 1 10w30 and was thinking of going to preferably a 10w40. I'd like to keep using Mobil 1 but, I see it is only offered as a 0w40. Any thoughts?

The reason for contemplating the switch is low oil pressure at idle. The Mobil did better than conventional oil, but I'd still like to see pressures a bit better than just above "the red zone" on the guage at idle and between 38-40psi when either cruising or under hard acceleration.

And yes I'm aware that the factory guages are somewhat innaccurate.

So any problems changing to a 40wt? And if so, which brand since I'd prefer to stay with a 10w40 synthetic.
I believe that engine would probably do very well using that oil, since the 3800 is based on an old design, and most likely has looser clearances than most new V6s do. It's probably the only engine left where GM recommends 10w30 instead of 5w30, so there's another clue right there. And with 120k on it, the need for a slightly thicker oil is there too.
I too have a 95 Buick with 120k miles on it, with the same motor/problem. Just switched from 10w/30 to 10/40 Chevron Supreme. Seems to have helped with the OP when warm ( and excessive oil use), but now makes a lot of valve train noise on start-up, when cold. And it really does not get that cold in August in Virginia! You would think that the thicker oil would not do that. I used the same Delco PF47 filter, so that should not be it. Maybe it is just a coincidence, and something new and exciting is going on in Buick motor land. Who knows. I was going to wait until it started to get colder, dump it, and try the 0w/40 M1 or one of the 5w/40 syns that are sold for the diesels.

Originally posted by Patman:
It's probably the only engine left where GM recommends 10w30 instead of 5w30, so there's another clue right there.

Not for 2004. Today, I had a chance to get a close up look at a 2004 Grand Prix GTP that has the supercharged 3.8. GM has redeisgined the oil cap, but "5w30" was clearly visible in the new white script.
Just add a quart of the 15W-50 to the 10W-30. A 30% mixture gets you close to a 40 wt. Don't forget though you will have a 10W or 15W. I'm thinking of your winters in Iowa.

Are you a Hawkeye??
Thanks for the suggestions thus far.

As for being concerned about a 10wX with our colder winters here - I run 10w in it year-round. Never any problems with cold starts in the dead of winter when the coldest temps we see are typically no more than -15F.

I'd probably just stick with a 10w40 syn of another brand than Mobil as the one time I ran 5w in it during the winter, the valve train noise was horrid.

Luckily I don't have an oil consumption problem or any leaks with the Regal. It uses about 1/4 quart between 4K mi changes. I never bother to add any since when I do the changes I always bring it right up to "full" on the dipstick.

It may have 120K on the clock, but it still runs very well, plenty of power on tap, tranny is in excellent shape, body is also in excellent shape with no rust, two minor door dings, two small scratches and a flawless interior. We picked it up 2 years ago for about $5,000 with 90K mi on it.

In short, we'd like to hold on to this car for quite a while especially since it rides so well now that we put on new struts and tires about a year ago.

Edit: And no I'm not a Hawkeye. I went to the University of Northern Iowa - raaagh Pathers baby (aw who am I kidding, our sports teams sucked at UNI).

[ August 29, 2003, 09:58 PM: Message edited by: Forkman ]
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