Just wondering what weight oil every one is using in there HP500 ( carb ).
The flame arrester says SAE40 but the book says 20/50.
Is there a big difference? ( in laymans terms ).
Thanks
Joe

No offense THATS IT, but this subject will give you so many responses your head will spin. It's been talked about and debated forever. I was going to respond that straight 40 weight dino oil is good stuff, but would say that full-synthetic is better in just about any way. I have been using Mobil 1 15W-50 for a long time with good results. Many have used Redline and Amsoil as well as Mobil 1 20W-40. In my opinion Hydrocruiser will give you the best answer and is an expert in the field. Either way, one of the more important factors is oil-change interval. Regardless of what you use, as long as you change it frequently you will save problems and reduce wear. Good luck

15-50 mobil one - I have never put anything in mine other then that. 500 hours and no failurs of any kind...plan on getting a lot more out em too.

Thanks

Joe

I have been giving the viscosity issue a lot of thought and have done much additional research. Here is where I stand right now on the topic:

Boaters using any "non-hopped" up application should be fine going with a premium conventional 30WT. If you want to go to a synthetic then Mobil-1 15W-50 is great; if you want what I think is the best overall choice then go with Redline 15W-40. It protects like a straight weight and being a premium synthetic outperforms Mobil-1 15W-50. Redline has much better load bearing qualities due to it's additive system. The hands down winner here. No slam intended towards Redcap Mobil-1; if price is an issue then use Mobil-1.

If you have a "hopped engine" then a conventional premium 20W-50 like Kendall or Castrol GT is worth a look. Mobil-1 15W-50 would be a jump up from any conventional oil. Depending on how hopped up it is I would cast a vote if you are running very hard and high HP engines you consider either 20W-50 Redline; 20W-50 Mobil-1 V-twin or 20W-60 Redline. The Redline
20W-60 having the best all around base and additive system.