Morris Minor Owners Club

Benny is booked in for MOT this weekend and Im about to do the service myself for the first time. Ive been shopping around for various bits n bobs (the service items etc) and got them all now except the oil.
I recall getting Duchams 20/50 at the Dorset MMOC rally last year and paid £8ish for 5 lts, not sure how much of an offer that was but then checked with Halfords and theior 20/50 was around £13, the a local motor factors had 20/50 (Millers I think) at £18 . Then I checked with a store in Christchurch (In Excess) who sell cheap tools and end of stock DIY items nd they had 20/50 at £7 (produced by Tetrosyl).
Does anyone have any words of wisdom / warning or recommendation about these different 20/50s?, are there any noticeable differences between them?, is it OK to use my old Duckhams and top it up with the cheap oil?.
I did a search using the word "oil" and got kerzillions of matches - looked through the first 10 pages and saw some discussion but the threads didnt really leave me any better off about the query raised but does make me wonder what SE SJ SM etc refer to in relation to oils?.
I dont want to put Benny at risk with a naff oil but then I'd rather pay £7 than £18....
As ever - all advice gratefully received.
Thanks, Mike.

The Tetrosyl stuff is fine - used it for years with no probs. just don't expect it to last for ever. Hellfrauds are ultra expensive for everything - that's if they even have it in stock!

I use duckhams Q... It was originally designed for A Series. If Dan is going to SADMOG tomorrow (and notices in time) you can buy on of my cans of Duckhams for £10 (I think I paid around £9.50)

Matt

I used to have a very useful link to another website that gave a good leymans guide to all thee codes, but when my PC got sick I lost all that stuff.

wonder what SE SJ SM etc refer to in relation to oils?.

The letters refer to how good the oil has proven to be after it has been properly tested. Buying an oil without checking the codes is like russian roulette - if the oil has no code then that means it doesn't pass the tests! Rubbish oil isn't worth buying unless you hardly ever drive and change it every year.

The oil additive people have invested millions of hours of reasearch over decades to make engine oil behave better than it used to. As a result they have to increase the test spec levels quite frequently.
SE, SF, up to SL and SM are the increasing levels for a modern engine oil. SF is better than SE and so on...

The point of these additives is to improve the thin film behaviour, reduces breakdown and also to help prevent sludge and dirt deposits that can damage your engine. This helps the engine last longer, but also helps the oil last longer [Therefore back to my previous comment that if you hardly do any miles (eg 2k per year) and change the oil annually then the codes are less relevant - you won't need the additives that makes the oil last longer!]

http://www.carbibles.com/ has about everything you could want to know about oil!

Minor H - just had a quick squint at that Car bibles site - it looks fantastic!!

Matt - Ive gone and got the £7 oil now ( )...looks like it should be OK as Ray has said if your mileage aint too great nad you change annually should be OK....thanks for the thought though

Ray - cheers for that the S codes is very helpful - best go and see if my cheapo oil has any reference

BMCEccosse - glad to har your experience of Ttetrosyl is good, I wonder if they do different qualities of 20/50? - cheers.