Best Oil?

What is the best kind of oil to use on a 1995 Buick Park Avenue? 161K miles. The high mileage synthetic stuff is so expensive, but is it worth it? Also, what weight and how important is the weight and in what conditions should the weight change if any?

What is recommended? Also, is it important to use the same kind of oil at each oil change? If so, why?

Thanks!

I believe the manual (wherein I know you have missing pages, possibly including these) indicates that you should always use 10w30, though some people will disagree for various reasons. In my 1999 Park Avenue Ultra, the manual says when it is cold enough (not to exceed 20°F), 5w30 should be used. I don't believe my 1993 Park Avenue manual said that, and I believe the 3800 Series II started in 1996, so if my 1993 didn't, your 1995 probably wouldn't.

Regardless, FYI, w means weight, and 10w30 means the oil behaves like a 10w oil when cold, but at 30w oil when hot. This makes it easier to start your engine cold. Some people feel that it would be better for the engine to use 10w40 or 10w50 and say 10w30 was only used to get better mileage because of EPA requirements (others figure 10w30 is part of planned obsolescence, wear out the engine faster).

I don't really know what the benefits of the high mileage stuff are supposed to be, so I can't tell you much on that. In general, I believe regular (mineral) oil breaks down quicker than its synthetic counterpart, though I have heard that regular oil is much better than it used to be.

Regarding what oil is best, you will get a lot of opinions from different people, and you will hear things, like for instance, "most mechanics use Valvoline in their own vehicles," which may or may not be true. I know a lot of people seem to swear by Mobil1 where I live, and I know some newer GM vehicles specifically say only to use Mobil1 on the cap. I figure GM has some deal with Mobil now, and I doubt they could legally void your warranty for using other oil in those vehicles, but I really don't know if either of those theories is true.

You will also hear "rules" like "once you use a synthetic in an engine, you should never use regular oil in it again," or "you should always use the same brand." I don't know how much substance there is to such rules, but my guess is little to none, though I am sure some people would swear they matter and be able to provide reasons, legitimate or otherwise, that certainly seem to make sense.

I hear "most mechanics change their oil every 3,000 miles even if the manual says 5,000-7,000 or there is an indicator," and I have even heard this from people who worked in car shops changing oil and spoke of the things they had seen when an oil change had 10,000 miles on it (without indicating whether it had been in the car for 3 months or 3 years).

In my 1999 Park Avenue Ultra, I use Valvoline SynPower 10w30, that is a full synthetic (high mileage is probably a blend, but I don't know anything about it), and I change it every 6 months / 5,000 miles (I don't think I've ever made it to 6 months without 5,000 miles). When the car starts losing a full quart in less than 5,000 miles, (it has 165,000 miles on it and didn't leak any until recently, possibly because it was overfilled), I will stop using the synthetic and just use cheap stuff (I have heard it is thicker, but not as slick, but regardless, it is cheaper), but all of that is just based on arbitrary decisions I have made.

The 1995 Park Ave has the series II engine..

You should use 10w-30 in this engine..

Mobil, Havoline, Valvoline and the like are all good oils and can be used... You can also go to the synthetic if you wish..

I have always ran Synthetic in my 3800 Series II and continue to do so... On the last fill I actually went to 10-40 Mobil 1 but will go back to the 10-30 Mobil 1 for the cooler months...

So as for the best possible oil I would recommend a Synthetic, but if you change your oil every few months you may want to run the regular oil.. I have seen 3800's go 300000 on Regular oil... So in the end the choice is yours..:)

Thanks y'all! :wink:

I know of some people that swears that 20w-40 or 20w-50 goes for everything!

I've seen various oils be replaced with 20w that clearly says 10w...that's one reason I was curious about it. I also was unsure of what brand is supposedly the "best", but I assumed that's a matter of opinion.

Thanks y'all! :wink:

I know of some people that swears that 20w-40 or 20w-50 goes for everything!

I've seen various oils be replaced with 20w that clearly says 10w...that's one reason I was curious about it. I also was unsure of what brand is supposedly the "best", but I assumed that's a matter of opinion.

The 20w-40 and or 20w-50 should not be run in the 3800's as the bearing tolerances are a bit on the tight side..


For the dead of winter I would say 5w-30, and for the warmer months 10w 30... If you were to live in a climate like Florida( like I do ) then you may consider 10-40..

But you will be good to go with your choice of 10w30:wink:

They all work fine. But If you do want a name brand that cheap go to NAPA and get their oil brand. It's Vavoline in disguise. Personally I use Pennzoil high mileage but now I think I'm going with the cheapest on sale next time.

More important than the oil itself is probably the filter you use.:wink:

More important than the oil itself is probably the filter you use.:wink:
:iagree: Good advice. All oil must meet minimum standards, so basically any oil in the store should do the trick. Over the past 20+ years I have used all brands of oil without any issues,( whatever was cheapest or on sale.) The filter is what you should be concerned about as it is an important part of the lubrication system. Here's a link to a study that was done on oil filters. There is some good info there:http://www.knizefamily.net/minimopar/oilfilters/opinions.html

Quaker State and Pennzoil are the same company.Run 10 w30 oil only in the 3800s.

I'm also thinking the shell oil is the same oil as Quaker State and Pennzoil since their all owned by SOPUS. Can't remember what everything stands for except the "S" stands for Shell.

What if you're like me and you go back and forth between cold and warm climates?

just best to stick with 10w30 eh?

Run what GM says to use.I do it all the time and no problems