Hi all,

Have a 1973 Triumph Tiger 750 (TR7RV), currently running on Autocare 5w/40 fully synthetic oil.
Having suspicions about the heat coming off the engine I was aiming to switch to Millers Oil XFS 5w50 Fully Synthetic; on the grounds that the original oil for these bikes was 20/50 - we used to use GTX - and the Millers oil covers this range.
Does anyone have experience of using a modern synthetic in 1960s/'70s British bikes, also bearing in mind that some oils state 'not for wet clutches'?

I can't really see why you'd want to use fully synthetic oil in a bike like that? I was once warned against switching to fully synthetic oil in a car (by a powertrain designer) as the detergents in it will loosen all of the grime that's built up and it all has to end up somewhere; generally in the pickups and can cause starvation.

We run all of our old bikes on normal, multigrade oils - bar a couple that are running on Castrol R. We sometimes switch from summer to winter grades if they run particularly heavy oil as they can take too long to warm, and run without good top end lubrication for too long after startup.

There are several oil companies that run 'classic' lines now, and we don't have any issues getting hold of any oils for even the most obscure 1920s bikes

If the engine has been fully stripped down and all the sludge traps cleaned out and you have a filter, I would say it should do no harm, but if all the traps have not been cleaned out modern synthetic oils will flush them out for you.

This is not a very good thing to happen as oil ways may end up being blocked.

Why not ask on the owners forum.

Found this http://www.classicmotorcycles.org.uk/technical/tec...