As long as you put oil in it IMO! Course 10w30 syn blend better and syn is would be even better, but does it last longer or can you keep it longer in a LT in a hot dusty envoriment?

The only way to know for sure when it have tested PPM for wear metals and silcon (DIRT). But, who is going to do that? it probably cost more than an oil change. SO IMO if it black and gooey CHANGE IT. IMO 50 hrs is way too long to leave oil in a LT. IMO I also beleive oil should be changed atleast twice a year regardless of hours and probably 3 times a year in extreme conditions (hot and dusty)Bottom line is; if it looks dirty it probably is as you have seen first hand with the engine failure due to dirty oil.

Course I'm an oil changing nerd and all of this is my opinion based on 40 years of mechanical knowledge and NEVER experiencing an oil related problem even on used equipment which most was pull out of the trash and brought back to life.

Well RC, you have some good points there. I seem to remember a long time ago my Dad or Granddad telling me to keep ALL the fluids changed and clean and I'd probably have few problems with engines. Wish they could have lived to seen them slapping these engines together today. Some good, some bad, I guess, but I usually get the bad ones.

I've got a 2003 GT5K that I decided to put in synthetic Mobil 10-40 in last year in July. Hey, I use Mobil 20-50 in my (air/oiled cooled) Triumph motorcycle, so I figure if it'll work in a $8K motorcycle, it's great stuff for my GT. I hadn't run that tractor more than 15 minutes in 95 degrees with 100% humidity and the motor sounded noisy and rattled to beat heck. I immediately changed back to straight 30wt oil and engine quieted back down to normal and was fine. I'm guessing that with how hot these engines get that it somehow thinned out the oil too much. Don't see how as synthetics were supposed to be better. Maybe if I used 20-50 it would of been fine, BUT don't know if oil pump and oil galleys could handle such weight oil. It's very possible that if you live in a cooler climate it would be fine to use synthetics, but here in mid-west Missouri, for some reason the oil just didn't work for me in the summer.

Just avoid oils with api service SM, there isn't enough zinc. Castrol is one that offers a choice, although I have seen way to many engines lunched on Castrol and won't buy it.

Well, now I am confused. I was expecting rave reviews from folks using synthetic. You might have a point about the cooler weather, although to hjear it talked up it sound like synthetic is the "next coming..." for all engines and dino's will go by the wayside. Hmmmm.

I used Castrol GTX SAE 30, but I average about 30 hours per season. Synth would be better if you use it more. Otherwise, I cannot see it, unless you are in a really hot area.

As far as the Briggs ELS, I had one of those mis-designed air-filter covers with the yellow flip-up handles. I found numerous threads on this problem, and then found one where a person was able to retrofit the engine with a new style intake elbow, blower housing, and screw down air filter. So, I emailed Briggs asking for the correct part numbers to do the retrofit. I wanted to purchase them and make sure my engine didn't fail. Well, they were so impressed with my trying to prevent the failure, that they sent the parts at no cost (considering the engine was a 2003 and I was going to purchase the parts). A couple of shipments and quirks to get the correct parts, and I completed the retrofit in less than 1 hour. Saved me about $120 in costs to purchase. I cannot complain about their customer service. That was about the best I have ever had.

For the past few years, I don't understand all the problems people are having with the yellow tab B&S air filter.
My 6 year old 24hp Intek has the yellow tab filter.
I inspect the filter frequently and always the intake plenum was clean and dust free.
I can see where someone not paying attention could attach the filter without having the front yellow tabs locked in.
The front tabs are locked in place with the filter cover at a 45 degree angle and then the filter cover is hinged down and screwed on.
Thats why they painted the tabs yellow so that you could see them sticking out of the front slots of the cover.

I think that synthetics have been around for decades and the old wives tales should have died out, but apparently not. 10W-30 oil meeting grade SG is 10W-30 oil meeting grade SG. Dino or synthetic. Change your oil at least per manufacturers requirements and use the correct weight and grade and you've done what you're supposed to do. More often doesn't harm a thing.

Synthetic should only be used for tougher conditions (AKA high heat) rather than as a reason not to change the oil as often.

The thing that causes the oil to turn black is "coagulated pentane insolubles".
Basically, it's soot.

When the saturation point of the soot in the oil is reached, synthetic oil will fail just like regular oil and the soot will act like a fine grade of emery cloth polishing the bearing clearances wider.

It is my impression that diesel oil still has a good amount of zinc, so I've been using 30-W shell Rotella. I figure if this oil can withstand the heat and combustion pressures of a big diesel, it should be fine for the 15 HP B&S I/C on my 33" Snapper YardCruiser.