I bought boat that has 2 teague 800's. I talked to the company that has maintained the engines for the last 35 hrs (all the hrs the motors have on them) and they told me they used moble 1 15-50. When I called Teague I was told to use kendall 50 (found a bottle in boat) or amsoil synthetic 15-50 If I remember correctly in one of Bob Teague tech articles he said not to use Mobil 1 since it will not let the roller lifters spin since oil is too slick and to only use Amsoil. Do you expect anything else from him since his sponsor is Amsoil? I have a friend that is a trouble shooter for Caterpillar that looks into why a 1million + dollar engines failed. He said all they use is mobile 1 and has not seen an oil related failure.

So what oil do I use?

if in warranty run what Bob Teague says. If noy I'd run Mobil 1 v-twin 20/50 hard to beat and works well for our climate

Whatever you choose change it freqently as fuel dilution will be the biggest issue. I'm using Mobil 1 V-twin although Eddie thinks that castrol 20w-50 is fine. He recommends on blower motors change at 15 hours.

I have a blower motor and was also told to run straight 50wt. Teague marine recommened straight 50 wt Kendall racing and another builder recomended straight 50 wt Vavoline racing oil.

Kendall GT 50 wt. That is the oil that teague has as a requirement in his warranty paperwork. I had his 1100 Quads in my 37 and currently have his 1200s in my 42. Kendall 50 wt is all I have ever run in his motors. I change the oil every 20 hours.

I use Joe Gibbs in all of my engines!

I use Brad Penn 50W. Your friend who looks at diesel Cat engines may not be qualified giving advise about gas racing engines. Change your oil every five hours on a big blower engine.

That's awesome! For years Teague says no synthetic, it causes bearing skate and doesn't work with roller lifters, blah blah blah.. Then along comes Amsoil and synthetic's great! But only Amsoil 'cause the other stuff's too slippery.. and who wants slippery oil right? right? No, wait.. uh..
If he was having trouble beating up lifters he probably should have looked a little deeper instead of blaming an oil that's been proven for years in the most demanding endurance races in the world.. I think you'd be fine with the M1 15-50 or 20-50.

It's all 3-in-1 oil, gauze pads and ball bearings these days!

He trouble shoots big natural gas industrial engines that turn low rpm. I agree there is a big difference in engines, but I was just thowing the info out there.