just got my engine back from full rebuild with some upgrades. Builder suggested running synergyn 15-50 full synthetic. Anyone have any experience with this oil?

Run what the builder says and keep the receipts. If it's hard to find, ask him how he feels about M1 V-twin 20/50

Ive been using Synergyn for years in automotive applications and always been happy with it. We currently use their Magnum line of diesel engine oil almost exclusively in all non DPF equipped trucks that we work on. When I raced we used to use their 15w50 in all the forced induction drag race stuff we ran and had good luck with it. Im guessing your engine builder probably sells it? If not it should be easy for you to find.........the local distributor Kinetic Petroleum that sells to the shops in the area is based in Mansfield.

thanks guys, yes its one of the oils he stocks. Just have never heard of it

What about amsoil or royal purple?

they were blended in Durrant OK by the dyson brothers. I use to sell their brands when they were very popular in the late 90's and up to early 2004. They were huge in the NHRA but that's because they gave a lot stuff away for sponsor deals they had their sticker on a lot of NHRA cars back then. They went somewhat to a name brand to barely not much sales within about 5 to 6 years.

A new person owns the company and I think he is out of AZ.

their 3 w - 30 was popular back then to. I actually still have some of their stuff but do not jump to use it. I did have oil analysis done on it back in the early 2001 and it was not bad results but not steller either compared to some other brands. Back at those timeframes I have good results with VP racing oils. So I stuck with that until VP stopped selling their branded oils,