Morris Minor Owners Club

Due to some technical gremlins I have just recieved a reply from Millers Oils to this email.

Sir,
After various discussions on a classic car website re the benefits of putting 20/50 engine oil in lever arm dampers, to increase the stiffness of the action.
I would like to hear your thoughts on the subject.
What is the difference between engine oil and shock oil?
Will engine oil damage the internals of damper?
Regards,
Ian.

There reply was as follows.

Hello Ian, I replied to your question round about the same or day after.
Why you did not receive I don't know. Putting 20w50 in a damper instead of shock oil will indeed increase the "stiffness" The difference is best explained this way the viscosity at 40 deg C for shock oil is 32.0 cSt and for 20w50 is 159.0 cst in other words it is approx 5 times thicker which will surely prevent the damper from operating correctly. Why not try a SAE 20 or SAE 30 in my opinion a better option.

Mike Fenton
Technical Services Manager

Hope this helps people decide.

" At 40 deg C " - the damper will never get that hot. But I agree - straight 20 or 30 would be better if you have some, the normal damper oil is SAE 15. So 20 won't make much difference - 30 is better and 40 is even better! But 20W50 will effectively be straight 20 at normal working temperature - which is not 40 C!

More replies from Millers Oils.
Question was.
"Hi Mike, Thank you for your reply. I don't know what happened to the original either. Gremlins.
One question you did not answer was would the 20/50 oil harm the internals of a lever arm shocker, ie rubber seals.
Regards,
Ian."

Reply was.
"Sorry Ian, the additives are compatible with the seals.

Mike Fenton"

Next question.
"Hi Mike, Is the difference in viscosity the same at working temps? Say 10-15deg C?
Ian.

Reply.
"Ian , oil is only ever analised at 2 temperatures 40 and 100 degrees C. The estimated Kv (Kinematic Viscosity) @ 15 deg C is 650 cSt too thick in my opinion.

Mike Fenton

~Hope those Q & A's help people decide what oil to use in there dampers.