Couple questions about my Craftsman

Hey everyone, I've got 2 questions about my 1990 Craftsman GT6000 917.254450 with an 18hp Briggs and Stratton opposed twin 422707. Has about 500 hours on it.

My first question is about the oil. I'm using Shell Rotella 5W40, I currently have about 45 hours on it and the oil is still as clean as the day it was put in and haven't had to add any. Being that it's advertised as "extended drain capable" I was wondering if I could extend to changing it every 75-100 hours instead of 50 hours?

My second question is about the transmission. It's a Peerless 820 that is hard to get out of reverse. Any thoughts about what could be causing this? Thanks

http://www.searspartsdirect.com/Cra...actor-Parts/Model-917254450/0247/1509200.html see page 25 after downloading manual, shifter linkage adjustment, let us know how it goes, thanks.

http://www.briggsandstratton.com/us/en/support/manuals/results?NTT=422707-1227* engine manual & parts list. I would stay with manual concerning oil change intervals, maybe you'll get another 25 years out of engine. Regarding transaxle, visually inspect all linkage first, if it looks ok lube all moving parts with oil squirt gun or Liquid Wrench Lubricating Oil in a can. I would also adjust valves on engine if not done in a while, specs. are in engine manual, engine cold.

The cheapest part you can put into your engine is oil.
Regular changes will prolong its life.
The intervals between changes will be dependant upon its actual useage & where it is used dust , temperature etc.
Down here where winter is the same as summer, just slightly cooler most do bi-annual oil changes because we use them all year round.
If you lay your mower up for any longer than a month then you should change the oil before you lay it up for winter.
just because you can not see any crud in there does not mean it is clean, does not mean that the addative package has not been spent , does not mean there is no acid by-products in it.