Looking at manufacturer's technical blurb regarding 2 stroke premix oils, it is difficult to decide on the best product to break in a new engine and then stick with. Oil manufacturers are all happy to state "up to ratios of 50:1" for "racing" products in both synthetic and semi synthetic oils.

I have broken in my new Beta on semi synthetic Silkolene Comp 2 premix - only because that's what was in the tank, but now need to change the mix to 70:1 as per Beta's recommendations.

So, firstly - who makes oil that can safely be used at 70:1 - Silkolene don't refer to such a product on their web site, and secondly Semi or not?

Are engine components really so fussy that either make a difference, or have I fallen into a marketing trap?

Semi-synthetic was recommended to me by lampkins at 70-1. They told me not to use fully synthetic in a trials bike, Rathmels also gave the same advice a few years back when we had a sherco.

Funnily enough we used Castrol XR77 which is a synthetic and never had any bottom end rattles on NYL's old Sherco. We continue to use it as well with no ill effects in the Gas Gas 125.

Funnily enough we used Castrol XR77 which is a synthetic and never had any bottom end rattles on NYL's old Sherco. We continue to use it as well with no ill effects in the Gas Gas 125.

A year or so ago, this fully vs semi debate was circulating. Several folks offered that they had been told by "Expert X, Y or Z" that trials engines don't turn enough RPM, or endure enough stress, to "need" or "burn" fully synthetic. Despite that, I have only met one person, over the years, that ran semi instead of full synthetic. Regardless of whether the bike was modern or vintage.

My advice..........stick with what the manufacturers manuals state........you wont go wrong!