Hi
I own a 1953 Humber Super Snipe Mk IV. The car's manual recomends a 30 weight single grade oil for an ambient temperatures of 45 deg F to 90 deg F. (It recommends different weight oils for different temperature ranges). However my local temperature can go outside the above range. Currently I am using a heritage non-detergent mineral oil of 30 weight. Should I be using a modern multi-weight oil and/or a synthetic oil.
The engine is a 253 cubic inch in-line six cylinder with overhead valves and push rods.
The car has 71,000 miles on the odometer however I don't know how many times it has gone around, probably only once. The car has a manual transmission with 4 forward gears.
Thank you for your answer.
Have not seen a Humber in ages, very few were sold in the U.S. The potential problem I see is not so much with newer oils being multi-weight (back in the day many car owners made the change from single weight to multi-weight with no issues), but the fact that you've been using non-detergent oil. This means there's going to be sludge in the crankcase and other areas of the engine that could be dislodged by modern detergent oils and cause internal problems. Back in the days when non-detergent oil was routinely used, normal maintenance included periodically dropping the oil pan to clean out the accumulated sludge.
For a definitive answer I would ask on a forum devoted to British Cars. There are some listed here:
http://britishcarlinks.com/british_car_forum_directory.htm
