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MG MGA - What type of oil?

I've a question arising out of Glens comments on MGA mods where he recommends synthetic 20-50W oil once the engine is run in. I always thought it was accepted wisdom that the MGA should run on a good 20-50W mineral oil and especially not synthetic oil for the gearbox. I wonder what other owners are running on then if thinking has changed?
John
J H Cole

John

I asked exactly the same question about 18 months ago. These were some of the responses:

http://www2.mgcars.org.uk/cgi-bin/gen5?runprog=mgbbs&access=&mode=archiveth&subject=6&subjectar=6&thread=200311101554263218

I decided against going totally synthetic purely on cost grounds - about £40 an oil change. I currently run on Millers semi-synthetic 20-50 at about £26.

Steve
Steve Gyles

Steve-thanks for the info. It seems that advocates of full synthetic oil presuppose an engine in good condition with fairly close tolerances. I can follow your logic in using a semi synthethic oil.
John
J H Cole

John

You may be interested in this post from Doug Hillary when discussing original oil specs

Quote
I did my Engineering training - six years - with BMC - in NZ and in England (Stewart & Ardern, "The Vale" Acton - 1962-63)

The export prototype Mini was my first development project in NZ in 1959
The tragedy of BMC was the lack of funds for refinement and, in the end funds were taken from the very viable Leyland Trucks Division to support the cash hole in the Car Division. However that was long ago and far away

Oil changes on the Mini were done at 1000 miles without fail - but they leaked SO much anyway it probably didn't matter much!
The OCI for other BMC engines was 3k miles max. and Castrolite (20w-20) or Castrol XL (20w-30) were the most common lubricants. Mobiloil Special 10w-30, or BP Visco-static were "not good" in these engines in the 1950-60s!

It is also interesting to note that engine life in cold and hot climates is very similar if the Manufacturers servicing advice is adhered too. Therefore, similar cars starting from a base low (cold) of -25C and +25C will almost always have the same engine life other factors being the same. Does this suggest that the design of the cooling system (for quick warm-up) and the Engineer's designed core temperature have much to do with the engine's ultimate life?


When the Mini came out in 1959 a specially formulated oil was required Duckhams 20w-50. It was the first "heavy" multigrade - 10w-30s had been out for years. You could use the same oil viscosity today in the same engine without an issue of course. We used 10w-30 20w-20, 20w-30, 20w-50 and mono HD oils in BMC "A" "B" and "C" series engines around the world in various markets without problems - as you could today. We got very good engine life at that time.
The '74 MGB I sold a couple of years ago ran well on 15w-50 and 5w-40 synthetics - the 5w-40 wasn't in the Handbook but met the original viscosity "intent" of the Handbook
The engine felt better on the 5w-40 though


the "intent" with the B series engines was to run as I recall 20-20W (Castrolite) or 20w-30 Castrol XL. We also used HD30 oils such as Delo etc. Later this included 20w-50 as these oils became available. We used 10w-30 too and had exceptional engine life with all of these mineral oils if the car was serviced reasonably well. I know of one doing well over 300k miles without work (except for a water pump as I recall)

The availability of synthetic oils changed all this
Unquote
Paul

This thread was discussed between 28/05/2006 and 31/05/2006

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