engine oil?

[Red Westie]

My mechanic (VW mechanic for 30 years) says for Aircooled engines Morris sae30 is best, plus so does VW (according to Just Kampers anyway),,,

Walk into any VW dealer in the UK today, tell them what vehicle you have and they will hand you a bottle of Quantum Blue 15W 40 mineral.
Interesting....and I can tell you from first hand experience as I worked at a main VAG (Volkswagen Audi Garage) in the 80's, we used what was in the pumps at the time, which was Castrol GTX 20W/50 (early 80's) and then later 15W/40 Quantum Blue out the stores department (mid eighties) onwards....NEVER A MONOGRADE...that dates back to early Bay Window as 'Thats all there was available' at that time.

When I say '15W/40 is far supperior in every way to an old 30 weight monograde' that isn't my opinion, it is just fact, lubricants have evolved and the 'best' available for an air cooled is 15W/40 or maybe a 20W/50 on a worn engine. later synthetics are too thin for old air cooled technology so 15W/40 minerals are the best compromise that give you the viscosity (thickness) required together with the improvements in additives ie: film strength/anti foam/detergent and viscosity index improvers.The improvements in oil technology that came about during that period (late 60's to early 80's, make 15W/40, 15W/50 & 20W/50 a much better product to use with your air cooled lump (note* 20W/50 would be an option for a well worn engine)
I don't really understand why any VW spanner would recommend 30 weight for a T25, VW simply never used this oil in a T25, and, the argument about 'the origin of the air cooled engine' just doesn't make sense....OF COURSE THEY USED MONOGRADES IN OLD BEETLES? SPLITS N BAYS, BECAUSE THATS ALL THERE WAS until the early seventies.....does that make this old oil better or more suitable? of course it doesn't, there was simply no choice back then.
It is also worth mentioning that when using monogrades it was common to HAVE to use two seperate oils, a thinner grade in winter and thicker in summer, thank god for multigrades I say...
Martin

Martin