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I will be stripping the my 1380 engine down over the winter and doing a full rebuild and was wondering if there are any pros or cons on the use of R40 vs good quality 20/50 oil, it is used for Hillclimb and sprints only.

Smell, that smell!!! Racing cars smelt better in the good ole' days...

I used Castrol R40 when I raced Minis in the seventies and eighties. I would never use it now because when an engine is static for a long while R40 turns solid and is very hard to remove. I now use Morris 20 / 50 classic, Miller’s Classic 20 / 50 and have recently used Duckhams 20 / 50 classic oil.

Alan

This topic was covered before, other than the smell I can’t think of one reason to run it. 20w/50 all the way.

Thanks for the input points taken think i will stick with good quality 20/50

I too like the smell of castrol r but I wouldn't even use it in the early 70s as Andy Barton put a 50 hillings surcharge on rebuilds. Given that he didn't use it on his 8 port headed 999 I thought he must be right, and clearlyt echnology had and has has moved on.
But because I hate cutting lawns I found putting castrol R in the petrol numbed the pain....

back in the day, a guy near where I lived used to put a bit of it in his fuel tank, a Fiat 131 Mirafiori Racing. No idea what it did to his engine but the smell was mouthwatering.

I had heard that it doesn’t like sitting around for long periods . I was told many moons ago that is gums up and it a pig to clean off. I did use Silkolene R 40 in my Hillclimb mini . This was different as it had some additional detergent added which kept it fluid. After 10 events I had to strip and change the crank due to flywheel fretting. The dogs were perfect and shells were perfect also. So can’t fault it. Though it wasn’t Castrol R.
Ian

I don’t have a sense of smell and little taste, after working with the older R40 you need a toilet extremely close
D

I think the latest R40 is modernised a bit with additives.
The advice from Castrol when laying the car up is to drain the sump, refill with fresh R40 then drain and replace that at the start of the next season.
Quite a costly exercise!

I tried R40 in my rally engine earlier this year but reverted to 20/50 when the LSD was clunking badly on slow turns. The clunking didn't improve and turned out to be just due to the preload.
Using it is a lovely bit of nostalgia rather than a practical or performance decision.

Andy

Castrol TTS (fully synthetic 2 stroke oil) used to smell just like the Castor based oils.
I don't think it is marketed by them now they have changed the names.
I went to Greece in 1978 in my Mk3 travelled back home in places, behind in particular a Datsun 240 Z (Acropolis rally car) obviously running on Castor based oil.

And just like time has passed for caster oil you might wonder why people stick with decomposed dinosaur food....

Cheers, Ian

In the late 60s Shell sold a sort of R40 "smellalike" called X1000 i believe it was mineral based so did not have the R40 drawbacks.I agree R40 smells great -but not after you have been following it for any length of time !!! Happy Sniffing. PETER.

Ronnie wrote: ↑Fri Oct 23, 2020 11:21 pm Castrol TTS (fully synthetic 2 stroke oil) used to smell just like the Castor based oils.
I don't think it is marketed by them now they have changed the names.

I used TTS in all my 2 strokes. It is now Power 1.
When out on bike, I would ride round a roundabout twice so I could smell myself

Stick a few percent Of R40 in the fuel Tank, although I don’t know how much you need to make it start smelling. Regularly run .5-1% two stroke oil to lubricate Lucas metering units but I can’t say it’s noticeable.

Like Oz I used to run Castor Oil in my Vespa - you are supposed to double the mixture rate on Castor - so 4% it was. At a huge scooter rally, whilst we were waiting for the ride out (I had to clear the engine occasionally, as the carb was set up for sea level, not 1000m above) - I got very mixed feedback from fellow scooterists surrounding me
Still feel sorry for the cyclists, who unintentionally went up Grossglockner pass road amongst us scooterists (2000! Vespas that was to be precise) in a huge stinky cloud of burnt 2-stroke oil.
BTW: Shell Racing M - which is synthetic 2-stroke oil with added castor oil is still available.
Castor oil imho beats every other oil in terms of lubricity, because of its longer molecular chains.

Going back to the original question id say it's not suitable for hill climbing as it'll never get hot enough, but that's only my opinion.

We changed my race bike from semi synthetic to castor oil and had no more trouble. It had the rocker fingers running directly on the cam and the rockers turned blue with heat.

Didn't Will Sparrow write an article In CCC in the 70's about his experience, when he changed to Castor based lubrication
detailing the difference in wear rates that he found on his mini's engines after a season of rallying ?