Iv got a 70 Plymouth w/ a 318 that has always used non-synthetic oil and i know next to nothing about oil brands so i was wondering where everyone stand on brands and why. also curious on these reasonings behind not using synthetic on a vehicle that always used non synthetic and vise versa that I'v heard about.

first thing i did when i got my car is put new castrol gtx 10w30 oil in it with a new filter(was on sale) but i did it with the engine cold which iv since found out was a mistake and the oil's color and thick nature coming from the engine makes me think it was neglected a while and I'm thinking i should do it over again. Since then iv put maybe 100miles on it.

 

I'm a Valvoline fan but, have been using the Castrol GTX "High Mileage" as it's supposed to have added zinc. Rick

 

Castrol 20w50

 

make sure that whatever oil you choose, it has zinc in it

 

You only need the zinc additive during cam break in if it's a flat tappet cam...after break in you can run anything you want...read labels...no off the shelf oil has zinc in it anymore...the one I run after break in is Royal Purple 10W-40 or 20W-50 depending where you live or how hard you hammer on it..Hughes Motors sells a synthetic blend with zinc in it but it is not off the shelf..

 

I live in mid Michigan, and your first person who uses synthetic so ill ask you, could it cause any problems with the motor if I were to run synthetic? not sure I will regardless of answer anyway but as far as I know the motor hasn't been rebuilt in 10+ years and has used non-synthetic oil. I'v heard swapping can cause leaks and all sorts of crap but as far as i know that's just rumors never heard of someone having it happen...

 

Old gaskets and seals....yes it will probably leak...only because it is slicker than conventional oil...you shouldn't use it on a brand new motor either until it is broken in for about 500 miles...you have to seat the piston rings first

 

gotta love learning new things, thank you.

 

Lotta folks say to run conventional during the first 500 miles. Yet the Vettes, and alot of other new cars are delivered with synthetic in them. Many new cars also have 5w/20 as the recommended oil! I dont think you can go wrong with any of the name-brand oils.
But what I WILL tell you, is that synthetic WILL NOT COKE under normal operating conditions. This will save you if you have a motor like the 2.7. Synthetic also does not "sludge" when contaminated by anti-freeze.

 

California climate. 93' roller 360 magnum in my 72 Satellite.

I broke the engine in with Wix oil filter and 10w/30w Valvoline for the 1st couple of oil changes. Then I put an above mild cam and springs in and switched to Royal Purple synthetic 10w/40w.
I noticed if the car sat for a week or two with the Valvoline, I'd hear the rocker arms or pushrods tap, tap, tap until the oil pressure came up.
After changing to Royal Purple, no more tapping on cold star ups.
Haven't seen or heard of any problems yet. Professionals use it religiously.
And I wouldn't recommend putting in crappy oil because it's on sale. You will end up paying more in the long run.

 

Okay I got smarter yesterday....Valvoline Racing oil standard weight and 20W50 has the zinc and phos additive in it...that would be good to run with flat tappet cams....there is another sold by XL parts but the name isn't in my head right now...the VR1 20W50 is like 9 bucks a quart...ouch...my 440 is a hydraulic roller motor so no zinc required...