The original owner's manual from my 1961 PV544 says,

"Use thin engine oil (SAE 10W)"

I think the factory knows best.
--
john

Many thanks for all the help on the damper oil. Seems like any light weight oil will do and driving the car will tell me what works best.

Bill

A guy who has a watch knows what time it is. A guy who has TWO watches is never sure.
This is the same kinda deal. Use whatever works best.
The amount of oil is the amount that gives resistance immediately as you start to lift the piston.
Too little, you can lift it a ways before you feel the resistance = NO HELP!!
Too much - it squirts out the top before the piston is all the way up.
You have to put more in from time to time but I don't know where it goes.
--
George Downs, Bartlesville, Heart of the USA!

how much oil do you usually need, or I should say how do I know I've got enough oil in there? I need to check and most likely top mine up.

Cheers.
Chris

The key, in my opinion, is first to understand why the oil is in there. Think of it as part of your accelerator pump assembly. The oil keeps the pistons from rising immediately when the throttle is opened. Thus, since the draft draws fuel from the jets, but the piston doesn't rise enough to "dilute" the richness of the mixture right away, you get the accelerator pump effect--a brief rich condition to get you over the hump of initial acceleration. If you consider that the heavier the oil, the longer it takes for the piston to rise and lean out the mixture, then you have the idea. The last poster has the key. Drive the car. Different temperature affects the oil and thus the rise of the piston. I've always used either 3-in-1 oil or hydraulic oil. Both are pretty thin. One needs to keep in mind that the ambient temperature is really only an issue on startup, when the engine bay is cold. When the engine is hot, the engine bay is hotter than it is outside anyway. Thus, using a thinner oil in cold climes isn't always good. When the engine is hot you may have a flat spot off idle. Too heavy an oil and the car may blow black smoke during acceleration from an over-rich condition. Too light and the car will hesitate from an off-idle lean condition.

Good luck. SUs are great carbs.

DS

I've always used ATF year round (-10 degrees F to 100 degrees F) and stock engines with HS6 and HIF carbs and never experienced stumbling problems.

Lots of opinions on this one, but this works for me.
--
'60 PV544, '68 220, '70 145, '86 745T

I always used Marvel Mystery Oil (10w), but have friends who swear by ATF (~5w).

You should be fine with anything up to 20w