A mechanic winterized my boat and put Amsoil synthetic oil in the engines. Someone told me that if the HP500's I have were equiped with Roller Cams, that could be bad...True or not?

thanks
Dan

I have never heard of synthetic oil being bad anywhere at anytime. Synthetic oil does not break down like regular oil. I have 2 600hp Super Charged 502 block roller motors and I use Mobil One Synthestic 15w 50. This was recommended by my professional engine builder. I think you should use synthetic, but with the correct weight that is recommend by your engine. I have not used Amsoil, but it is suppose to be some good stuff. Too expensive!

Bob Teague did a write up on this in Power Boat. He recommends Amsoil but, had a specific type for the hydraulic roller motors. Call Teague Marine.

I ran 5w50 Castrol syntec in my 500 HP 454 with roller cam and rockers from post breakin untill I sold the boat last spring. After 11 seasons of running everything was A-1

I tried like hell to break mine this year running synthetic, couldnt do it!

I ran Amsoil in my HP 500's for 250 hours
without any issues.

i use royal purple in my 500 efi's , have pulled the heads and replaced springs and valve job, no wear on roller's on the lifters, the Teague article said that they have noticed on some hyd. roller motors with low spring pressure the roller would not turn[roll] it would skid instead causing a flat spot .

You'll be just fine. Just make sure what oil he used. It should either be the Dominator 15w-50 Racing Oil or the 20w-50 High Performance Oil (ARO). Those are AMSOIL's highest zinc and phosphorus oils, which are specifically designed for the rollers. If you have any more questions feel free to shoot me a PM. I can you get some data sheets on any and all products also.

A myth started by Merc before they had their own synthetic oil to sell.

exactly !!! and they don't make it now...just re-packaged and uped 40% !!!! I run moble 1 or royal purple