Outdoor Power Equipment (Lawn Mowers, Snow Blowers, Chain Saws and more) Discussions

I'm not exactly Mr. Goodwrench, but I do perform all(most) of the maintenance on my OPE each spring.  It's amazing how, with the addition of new toys, this job takes longer and longer.  Instead of me traveling to several different dealers for when I only need spark plugs, is there a website (Champion, Bosch, Autolite,etc.) that allows you to list brand "A"'s spark plug model and then it would give you the equivalent model of their plug you should use?  It sure would be nice to get all of my spark plugs at one time....

PaulR

PS..does anyone know how frequently the hydrostatic transmission fluid in a Deere GT225 should be changed?  Has anyone done it or is this best left up to a dealer?