Guess you don't have a restricted exhaust problem! Get some good numbers together and post them. Lot of sharp guys on this site to help you with troubleshooting.
It's my first post but somebody is on to the right lead, because you instrument cluster voltage regulator is on the fritz, happens in my 84 from time to time. The regulator is changing voltage causing both the oil and temp gauges to read higher then normal, I bet if you pay attention I bet your fuel gauge reads higher as well. Start with the simple things first the regulators are cheap and are known to go bad.
Temp haulage does this as soon as the truck starts. Oil stays abou this unless I'm Dickinn off and revvin it up. Gas gauge is a little iffy. Speedo gauge is off for sure. I was going about 25 and it said 10. Then was goin about 10 and it wa at 0
That temp gauge is pegged and its due to the cluster regulator beat the dash lightly with a fist and sometimes they go back to normal.
Or your sender shorted out.