Castrol R racing oil

[coldplugs]

Castrol R - Why'd we use it?

I'm sure most of the old timers will vividly remember the smell of Castrol R racing oil. It was so distinctive that attending a vintage race today is a little like watching a silent movie of the real thing. No smell of castor oil and (usually) no smell of burning rubber.

(I know it's available again, but it's not the same stuff).

My question however, is: Why was it so popular with the racing crowd. Everyone seemed to use it but I'm not sure most folks know why. My impression was that it burned cleaner - it didn't leave as many deposits on valves, piston tops, and combustion chambers. This was important because the loose clearances most engines had back meant they burned a fair amount of oil. Is that right?

Anybody know?

 

[Dave Russell]

Hi John,
I think it was because castor oil had one of the highest film strengths available at the time. It does NOT burn clean, & leaves enough residual gum to require cleaning/flushing it out of the engine very frequently. There is no denying the wonderful smell of castor oil though, especially when combined with burned nitro fuel. One of the greatest smells on earth, to my somewhat warped sensibilities.
D

 

[piman]

Hello CP,

yes, as Dave says, it was because of it's superior lubricating qualities at the time. It was generally a racing oil because of all the laquer which made it impractical for use in road engines.

I also agree with Dave about the smell of it, I can still experience it at Vintage (U.K type vintage that is) race meetings.

Alec

Alec

 

[Roger]

I used it in my A7s because of its film strength and also because it never seemed to foul plugs as readily as mineral oils. With low-pressure spit-and-hope lubrication, white metal cast-in big ends, I didn't want to be re-metalling rods too often. The only big ends I ran were with mineral oil.
I'm surprised it doesn't burn cleaner, but maybe that's not the issue.
Pre-war engines were very fussy about plugs, and my ring clearances were always generous. I could run harder plugs with 'R'.

 

[coldplugs]

[ QUOTE ]
...
I'm surprised it doesn't burn cleaner, but maybe that's not the issue.
Pre-war engines were very fussy about plugs, and my ring clearances were always generous. I could run harder plugs with 'R'.

[/ QUOTE ]
That was our experience also. We had a Climax FWA that was really fussy about plugs - they were either too hot and the thing would barely produce power for more than a couple of minutes or they were too cold and fouled. The Castrol R seemed to reduce the fouling & that's where I got the impression that the stuff left fewer deposits.