Oil cooler delete- time for heavier oil?

Feb 18, 2022
I just bypassed the oil cooling system on my 1989 silverado, 350/4wd after dealing with leaky lines and bad fittings from the start. It finally blew out a fitting going down the highway so i figured any advantage the cooling system has can't possibly outweigh the damage of losing losing my oil going down the highway.
More to the point of my story, though: Since the oil is now conceivably going to be running at a higher temperature, would this warrant running a heavier oil? The truck has typically gotten 5w30 winter, 10w30 spring/summer all dino oil and tolerates it as well as you could ask a 30 year old truck to. Burns a little but thats to be expected. Should I kick it up to a good 10w40 or similar weight at this point?
One time I noticed oil leaking from my cooler line fitting on my 93 GMC with a 350. In ordered a new set of lines and replaced it, but it was a bear getting it in place while lying on my back. On the other hand, I’m running 5w40 in my other truck which is a LS 6.0 with 225,000 miles.
No problem running it w/o an oil cooler. There's also no problem running it on something like Mobil 1 0W40, or a good 5W40 either. If it were mine Mobil 1 0W40 would be in the sump.
oil coolers are really only for heavy use like towing and prolonging oil life. But that engine will be just fine without an oil cooler. i run 15w-40 or the very occasional 5w-40 in my 03 and 05 with no issues. Don't see how you cant.
The crimp fittings are a known fail point/leak point on Chevy trucks with oil coolers.
This happened a lot in the 6.2 and 6.5L Diesel Chevy engine in 80s and 90s diesel.

The problem is not just the fitting (metal to rubber crimp) but the quick connect at the oil pan.
Over the years, they just let go.

In my case, there are aftermarket who sells one with threaded fitting and steel braided hose.
The fitting on the cooler side is also non-standard.

It has buried a lot of engine when that quick connect let loose on the street.

I know I don't answer OP's question, though.
Just stating the fact that if you have this vintage truck and want to keep it, it needs better fittings for the oil cooler.
The diesel truck cannot be without that oil cooler unlike the gasser.
If you have an oil pressure gauge you are in luck. Use the oil grade that gives you 10 - 15 PSI per 1,000 RPM for whatever your load happen to be, when your engine is warmed up and the temperature stabilized. Water temperature does not count, use oil temperature or wait 15 - 20 minutes of driving.

Oil cooler is noy really needed unless you are towing. It must be a 3/4 ton of the "heavy half" to have a cooler.

The oil line fiasco was across the board in many GM products. The Blazer with 4.3L had a remote oil filter with the same rubber lines. They would leak/blow off as well. They crammed that V6 in there where a 4 banger was supposed to go.
They all leaked. My 1998 Chevy I removed it. The dealer replaced the lines and they leaked again. We decided to remove them. The engine ran to approx 500,000 kms before the truck was scrapped. I wouldnt be too concerned about that oil cooler. The truck ran 5W30.
On my old car builds with remote filters or coolers I use hydraulic hose and hydraulic fittings. Local parts store makes them, not an option for GM OEM applications, but those never leak.