Hey Scotty love your channel and the good work you do! I am highly addicted to it and you saved me lots of time and money and taught me things never knew existed or even possible, keep up the good work! I just recently bought a 1970 Cadillac Sedan De-Ville with 18,000 original miles with original equipment including a/c compressor which blows super cold, v8 engine. It drives perfect no problems or nothing. I was going to change the engine oil. I couldn't find the engine oil they want to use. Upon reading the dipstick it calls for 4 quarters of a GM oil with no viscosity. I cant even recall what it said. Any recommendations on what kind of synthetic engine oil I should use. I live in NYC Bronx climate to better help you determine. My other question is regarding the transmission since it has 18,000 miles I want to preserve the transmission by changing the oil. Any recommendations how often should i drop the pan and what kind of oil I should use. Thanks for the help.
I would never use full synthetic on an engine never designed for it. The main seals will probably start leaking immediately. See if you can find regular mineral oil or at least a high mileage blend in the 10w40 weight range.
Any good 10w30 or 10w40 oil should be fine for that engine. The problem with synthetic is that it flows so well if the seals in the engine are the least bit questionable it will leak. With only 18K miles you may be OK but age takes it toll as well as mileage. (I have used synthetic oil in 1960s-vintage V8s but after they've been overhauled and have fresh seals.)
On a 1970 GM car the original transmission fluid would be Dexron, which replaced Type A Suffix A. You should be OK with Dexron II or Dexron III formulations, frequently marketed as Dex/Merc.
For engine I say get full synthetic oil
For transmission since it is a v8 get super F
