There was a rather convoluted thread on using Castrol R 30 in diesel fuels on the Barton forum recently.

See: http://controlline.org.uk/phpBB2/viewtopic.php?t=5942

I'd agree with John, its fine with ether based diesel fuels, but a bit problematical with glow fuels. A mate and myself bought some a while ago when we couldn't get Castrol M. We got it to mix ok with methanol initially, but overnight it stratified in the fuel container.

If your local dealer can get Castrol R-30 they should be able to get Castrol M as well. It mixes readily with both.