I have a 1995 chevy beretta with the 3.1 and its the base model... I am needing to know what oil weight is best for these cars? It has 230,000 miles and going good (: just need to change this oil. I have been taking it somewhere to get the oil changed and they been putting 5W-30 in it and it's just too thin..... Please help me!

 

Why do you think it is too thin?

 

Well... Mainly because after like 1000 miles our check engine light comes on after the oil change of 5 quarts.....

 

my oil light not my check engine... sorry: )

 

Is the oil low when the light comes on? The engine was designed for 5w-30. It is an old myth that when an engine get older use thicker oil.

 

for my 90 beretta with over 200,000 miles.
In the winter I use 5w-40
In the summer I use 10w-40.
To correct a previous post, sometimes it is true that an older engine needs a bit heavier oil, the 40 weight hot solved my lack of oil issue in my 90 Beretta's upper parts, I'm not the first owner of this car, the engine was not taken care of as often as it should have been. It is worn out enough that the thicker oil is needed in my case. (I got it really cheap for a parts car, but due to some events, I rebuilt almost all of it to be my usable car).

But 30 weight hot is okay, I use 5w-30 winter and 10w-30 summer in my 96 Beretta with a brand new rebuilt engine. Because here winters are below freezing and summers are over 100...haha

I also put 1/2 quart of the phosphorous additive in the Beretta's. Their engines were not designed for the ILSAC-GF4 requirement in all new oils.
That requirement removes what our engines need from the oil.
True for all Beretta's 87-96.

 

Do you have an oil pressure gauge in the dash? If so, what are your readings?
An engine with 230k miles is likely to have an amount of bearing wear. That wear (excessive clearances) lowers your oil pressure. Using a higher viscosity oil will give you more of a cushion of oil, increase the oil flow resistance between the bearings and journals (part of what determines oil pressure), which will help to raise your overall oil pressure. But first you want to figure out if you're experiencing low oil pressure in the first place. Your issue could be something as simple as a faulty oil pressure switch.

 

Yes my oil pressure was low.
My rockers, maybe the cam, I was starting to get some clatter after using the engine for almost a year.
The 40 weight hot solved my issue, no more clattering, and better oil pressure.

The prosperous additive is a big help too, without it the ILSAC-GF4 spec oil is like water & runs off easily, with the additive, the oil sticks to the parts better.
It specifically says made for vehicles that were built before the ILSAC-GF4 spec vehicles design came about.

The engine is still very smooth, runs like new, it was just lacking in oil pressure.
I have a newer hardly used 3.1L v6 in a mint 90 Beretta INDY that is garaged, it does not need the 40 weight hot...

By biggest issue is that the 90 Beretta was built before synthetic oil went mainstream. So I use fossil oil, I'm worried the synthetic will eat my gaskets. However I do mix a small amount of synthetic oil, 1/2-1 quart at the most to help prevent buildup. My 96 Beretta with the brand new rebuilt engine, I put full synthetic. It has all the new gasket designs. That was after the breaking-in period.
(I have came across many people who had to rebuild their engines because the synthetic oil ate the gaskets, so I'm playing it safe till I get better info).

But I had to work up to using synthetic in my older 90 Beretta with over 200,000 miles, a dirty engine can be catastrophic if you put too much synthetic oil at once...

My oil pressure reader is fine, it used to be broke and reading over 80 PSI all the time. haha
Now it reads about 60 ish. It used to read about 20-25...
When I got the car, the old sensor was unplugged and hot-wired so the car would still start because they were to cheap to change the sensor.
(I got the car from hill-billies, you dont want to know every dum thing they did to the car, and filthy thing....ew).