Thomabear
Silver Member
I have an old Yamaha ATV that I purchased real cheap to leave at our hunting camp. The mfg recommended 30 or 10w30 but that machine was so abused and sludged up that I wondered if the oil had ever been changed. Since I didn't have much invested I decided to change it out with 15w40 diesel oil since it was available on location and I thought the robust detergent package of diesel oil might help to clean things up. Long story short the 15w40 worked out great so I'm still using it. It has now been about 7 years to date and she still starts 1st crank and runs great.