I have a Kubota L3400 Hydrostatic Drive with a front loader. I have used my dealer for service oil changes till now. I want to change my own oil and eliminate a trip hauling my tractor to the dealer. What is the recommended engine oil that I should use and where can I get a compatible oil filter other than at the Kubota dealer? I have about 160 hours on my tractor and it is about 8 years old. Thanks.