Amsoil also makes a 30wt/10w-30 synth(Amsoil ACD and ASE). Not pushing Amsoil, but its out there as well. Gotta say though, German Castrol 0-30 has been rock steady in my small engines over the last 3 years.

I have a caveat about switching to synthetic in an older engine: Do it by the book or don't do it.

My buddy talked me into switching my V8 with 150K miles on the engine to Amsoil. I didn't flush the engine like I was supposed to and within a week it started hammering. The cleaning effect of the synthetic oil wiped out all my bearings. My newer V8 has been run on synthetic since new and has 135K flawless miles on the engine.

is it straight 30weight? 10-30 is too thin for florida heat

I hear a lot about "Florida heat" or "Texas heat". Is 98 degrees hotter in Texas or Florida than it is here in Tennessee? My limits on doing yard work are 32 degrees in the winter and 98 in the summer.

That being said, Briggs & Stratton recommend and sell 5W30 synthetic oil for their engines, and state it is their first choice recommendation for temperatures between -20 and +120 degrees. Does "Florida heat" get any hotter than that? By the way, the last time I checked, this B&S oil does not carry the new SM rating, a formulation designed to protect catalytic converts on cars. Neither does the Amsoil 10W30/30 small air-cooled engine oil.

Rotella or Delo 15w40 for all of my small engines!

I second the comments and observations of dpunisher listed above. I am a bit surprised that someone else on this board uses German Castrol Syntec 0W30. Word of mouth sells, I guess.

Using German Castrol 0W30 in my air cooled Briggs generator and Briggs powered mower in 90F temps I have noticed:
1) Quieter and smoother running engines. (noticeable enough that my wife thought I "did something" to the Toro mower).
2) Less valvetrain noise upon startup. Less "ticking" sounds after shutting the engine down.
3) Cooler running engine (if the hand over the engine tests counts for anything).

Of course, I can't say if either engine will last longer than normal. Ask me in 10 more years.

My observations are compared to Mobil 1 and straight 30 wt mineral oils, which I used before. As a side note, some Corvette owners have also switched to German Castrol 0W30 and found the first two listed observations, as well. If you see it in your local Autozone (it should say "made in Germany" on the back), grab it. I heard it is being discontinued.

I use Mobil Delvac 1300 Super in 15W40 for my small engines same as used for my Kubota BX2200 diesel tractor. This is a diesel engine oil like the Rotella but it has a lower pour point and will work in colder weather. You need a heavier weight oil in an air cooled generator these are run under a higher load and get a lot hotter than a lawn tractor engine.

By the way it was a high of 98 degrees here in southern New Hampshire yesterday and just as hot today. Only difference between here and Florida/Texas/Tennessee is that we also get 10 below zero in the winter.

I run my Kubota tractor 12 months out of the year on the Delvac 1300 Super oil and it starts right up in below zero weather.

I have heard good things about the Amsoil ACD synthetic though.