Batman 357

I've read through the permanent posts and still have an oil question. What would be the preffered viscosity or weight for a 1969 350HP 350 CI 4 speed car that seems to be pretty much stock. I’ve had the car about 6 months. Oil looks great but prior owner did not have any further info.

The car is a weekend driver in Oklahoma. The C3 had such a long production life oil recommendations and technologies had to have changed a bunch. My search feature does not work so I had to give this a shot. Thanks...

Calo69

I have exact same combo 10w30 is what has been used in car 30 yrs. 70k mi.

7t9l82

I live in Florida and I run 20w50 synthetic year round.no doubt some will chime in that you should never ever use that oil. I simply will reply with my word of the month "HOGWASH".

briankeery

20W50 is listed in the owner's manual, good enough for me.

gungatim

I use 10w30 in my climate. used 20w50 once in A 350 Monte carlo one winter when I was a teen and destroyed my lifters on a low mileage engine...I know people use it, but I don't care for oil that thick...remember it's a balance of pressure and flow(volume). too little of one or the other can be a problem...

fishslayer143

10W30 .....or 10W40 in very hot climate

zwede

In OK a 10W-30, 10W-40 or 15W-40 would all work well. You could start with a 10W-30 and see how you like the idle oil pressure and oil consumption. If it's fine, stick with it, otherwise start moving up in viscosity.

resdoggie

What? No mention of ZDDP guys?

OP, You need to determine if you have a flat tappet or roller cam seeing you don't know much about your engine as you aren't the original owner. 10W-30 is fine but whatever brand you intend to buy, google search it first to determine the amount of ZDDP in the oil. Lots of info (and lots of controversy over whether its needed) on this in the forum here and on the internet. Then you also need to decide if you want to use synthetic oil. You do not need synthetic for your engine but it's an option.

Batman 357

I know to use high zinc in an old car. It leaks a little so I'll pass on the synthetic. Pressure is on the high side now when motor is cold. Pegs the meter.

lurch59

Viscosity requirements are largely ambient temperature dependent. I doubt it gets very cold in Oklahoma city, any mentioned will be fine. I would not use 5w20, however.

BTW the "W" in the oil viscosity stands for winter, not weight. This is to be used to compare viscosities of oils for the lowest recommended ambient temperatures the engine will encounter. There are charts to help you find the oil best suited to your climate.

DUB

ALSO...keep in mind the oil change interval. Some oils will have a 3000mile/6 month change interval...while if you go with some synthetics ( I use AMSOIL Z-ROD 10w30)...you can go a lot more miles and have your oil change be a year. Do the math...if you are concerned on the cost...and include your filter. Then make a decision.

DUB

lurch59

I agree, and Amsoil likely has a filter you only have to change once a year. You will also save a little bit of fuel with synthetics......

Batman 357

Thanks everybody for all the info.