Morris Minor Owners Club

I orederd some oil today from my mate who runs a garage and what turned up was synthetic 20w 50 not mineral, should i avoid it or will it be ok?

I have not seen or read any reasoning not to use the synthetic SAE20/50W engine oil.
The 'A' Series was designed for use with mineral oil but things have moved on since then. So to reiterate 'use and enjoy'.

Thanks Phil

That's interesting, I was advised to avoid modern oils with a high content of detergent in them. For my 1948 MM with sidevalve motor I use Penrite Shelsey Medium (the car and I are located in Australia). Is that just marketing or a good idea? Is the A series engine a different story, being made up to the 1980s albeit in modified form?

I have in the past been involved with cars fitted with petrol engines using detergent diesel engine oil in the sump. No problems with using diesel engine oil but it does require the oil filter to be changed at the correct service intervals. The detergent keeps the inside of the engine nice and clean and makes sure that the crud get caught in the filter and not allow it to settle in the bottom of the sump.
So to answer your question - in my experience oils having a proportion of detergent in the composition have no detrimental effects on petrol engines.

philthehill wrote: ↑Sat Jun 04, 2022 9:06 am I have in the past been involved with cars fitted with petrol engines using detergent diesel engine oil in the sump. No problems with using diesel engine oil but it does require the oil filter to be changed at the correct service intervals. The detergent keeps the inside of the engine nice and clean and makes sure that the crud get caught in the filter and not allow it to settle in the bottom of the sump.
So to answer your question - in my experience oils having a proportion of detergent in the composition have no detrimental effects on petrol engines.

I don’t believe the concern is regarding the amount of detergent, per se, at least in cars with full flow oil filtration. It is more the concern around using a detergent oil after an engine has been run on non detergent oil for many years, as some worry that it can dislodge lumps of sludge that have built up over the years and then cause issues.

If you’re running an early Series MM WITHOUT an oil filter, or a Series II with a bypass filter, a low detergent oil is better, as it doesn’t keep particulate matter in suspension in the oil like a detergent oil does, meaning that rather than being circulated around the bearings (particularly bad if they are soft white metal) and NOT being filtered out, the crud settles at the bottom of the sump.

So, as a rule of thumb, with no oil filter - non detergent oil is better, and for any car with a full flow filter, detergent oil is better.

Yes that makes sense. I'll continue using the Penrite oil. I also change it every year even if the car has done 500 miles in that time, due to the lack of an oil filter. The engine in my 1948 MM lacks both oil filter and water pump. (Amazingly the car does not overheat on 35C days, the circulation of water through that huge radiator due to convection is effective, though at that temperatures it's too hot for me. Also, not having a heater isn't a problem in Adelaide).

Whilst I agree with some of the comments regarding the older Minor engines with poor filtration - I believe that I am correct in saying that olderisbetter has a modified 1275cc MG Midget engine installed in his Minor which has a full flow filtration system as standard so basically my answer to the OP question was in regard to that 1275cc engine which will quite happily run with the SAE 20/50 synthetic oil as shown above. So again I say use and enjoy.

Well, Oldisbetter,
Pete Bags expressed it well here a couple of years ago when he wrote “I often feel the old car is a bit like me - I could use the medicines suggested when I was born, but I'll happily use the more modern ones, as I feel they will keep me alive for longer!"
And you have fitted magnets in the sump plugs, haven't you? (All plugs - engine, gearbox & backaxle!)
Regards from MikeN.

A fellow on the internet rebuilt his old jeep (1950s I think ) and ran it for over six months using synthetic engine oil, he said there was no after affects of engine wear using the oil.
regards
Billy

MikeNash wrote: ↑Sun Jun 05, 2022 4:04 pm Well, Oldisbetter,
Pete Bags expressed it well here a couple of years ago when he wrote “I often feel the old car is a bit like me - I could use the medicines suggested when I was born, but I'll happily use the more modern ones, as I feel they will keep me alive for longer!"
And you have fitted magnets in the sump plugs, haven't you? (All plugs - engine, gearbox & backaxle!)
Regards from MikeN.

Thanks Mike - indeed, just like my gearbox (fully synthetic Redline MT90) I'm using fully synthetic engine oil. It's Millers fully synthetic 20-50 Pistoneeze, amongst other benefits, it's molecular formula (different to mineral oil) has the advantage over the ZDDP of leaving a better protective covering which lasts longer on the engine internals, so ideal for protecting the engine when it is not used for extended periods - eg over winter etc. Like the ribbed gearbox, my 1098 engine has now covered around 10,000 miles using synthetic oil, and it seems very happy for it.

Strangely, I'm still using EP90 GL4 mineral oil in the diff - unless someone knows of a better synthetic oil to use!

All the best, Pete

MikeNash wrote: ↑Sun Jun 05, 2022 4:04 pm And you have fitted magnets in the sump plugs, haven't you? (All plugs - engine, gearbox & backaxle!)
Regards from MikeN.

Hey Mike,
You remember those three magnetic drain plugs you gave me a while back? Pleased to say that oil changes show practically no swarf at all on the magnets, so thats a good sign!
Cheers,
Pete

That is correct Phil this oil is going in the MG engine, The other cars i have are running 803cc 948cc and 1098cc but i have kept standard morris oils mineral in them.