Small Engines (Lawn Mowers, etc.): Synthetic Oil for Kohler Twin 25HP motor, synthetic engine oil, craftsman gt5000

Question
Hi John,
Thanks for all of your great anwers on this forum.  I did some searching but
couldn't find answers specific to small engines for my oil questions below.  

I have a Craftsman GT5000 lawn tractor, with a Kohler twin cylinder 25HP
motor in it.  The Sears model number for this tractor is 917.276012; its serial
number is 6311048001749.  I just bought this tractor used and think it is
about 5 years old, but it has been used only a few times.

Can you tell me the year of manufacture for this tractor?  I would like to
replace its engine oil and 6 speed manual transmission oil with synthetic
lubricants.  Is this advisable to reduce wear on the engine and transmission?  
Can you suggest the manufacturer/type and viscosity of oils to use?

Thanks for your help!

Steve

Answer
Hello Steve:

I Use SAE 30 or SAE 10w30 Mobile 1 Synthetic Engine Oil in All my Equipment. Most of the Manual Transaxles Use 80w90 Gear Lube or SAE 30 Engine Oil for Lubrication. You Should be Able to Tell from the Viscosity of the Lubrication that is Removed from the Transaxle if it is 80w90 Gear Lube or SAE 30 Engine Oil. Like you, I Prefer the Synthetic Oils because they Reduce Component Wear and I Get Longer and Better Service from the Equipment that it is Using in. I will Check the Year Model as Soon as I Get the Microfiche Machine Running Today and will Send you a Follow up to this Answer. If you Hit a Snag or this Does Not Correct the Problem,  I am Here if You Require More Assistance. Hope this Helps. Let me Know What Happens, Please. Have a Happy Holiday Season and May the All Mighty Bless You and Yours. Be Safe and Happy. Thanks.

Good Luck

Respectfully

John

PS: I am Allowed to Answer 10 Questions a Day. If you See I am Maxxed Out, then Try Submitting your Question at or Just After 8pm EST (US). My New Day Starts then. Thanks.

Respectfully

John