Castrol Power1 4T 5W-40 Full Synthetic Motorcycle Oil, 1 Quart, Pack of 6

Can’t beat this for quality and value.

Harley twin cam 88 seems to like it runs quieter, I think so anyway, like Castrol oil but hate the foil seal on bottle,my advice is to use a funnel with screen! you don’t won’t any mishaps with foil in oil tank.

I'll be damned if I'm going to pay what Indian wants for their 20w40 oil for the Thunderstroke engine. 52,000 miles with this oil and it's been great. Oil changes at 5,000 miles as recommended for the OEM oil, and I never have to add oil in between. Blow by into the airbox is the same as the OEM oil. Cold starting is the same in the winter (mornings as low as 25F). I also ride in 120F-plus desert weather, which is hell-on-a-hotplate, but the bike handles it better than I do. I've even used an IR thermometer on the cylinder heads and seen no difference between OEM oil and this, with hundreds of readings taken at different times and ambient temperatures. Clutch and shifting action are unchanged between Castrol and OEM. I've also used Valvoline's V-twin oil though and noticed no difference, so this is certainly not a religion for me. It's mainly that Castrol as a good V-twin oil and a good high-zinc oild for my air-cooled VW Baja Bug, so I stick with them out of habit.

as expected, box of jugs of oil

Castrol Power1 4T 10W-50 Full Synthetic Motorcycle Oil is a premium lubricant that is designed to meet the demanding needs of high-performance motorcycles. This oil is formulated with advanced synthetic base oils and Castrol's proprietary Trizone Technology, which provides superior protection for the engine, clutch, and gearbox. Castrol Power1 4T 10W-50 is a shear-stable oil that maintains its viscosity under extreme conditions. This helps to ensure that the engine is always properly lubricated, even when riding at high speeds or in hot weather. The oil also has excellent anti-wear properties that help to reduce friction and wear on engine components. In addition to its outstanding performance, Castrol Power1 4T 10W-50 is also a very clean-burning oil. This helps to reduce the build-up of deposits in the engine, which can lead to reduced power and performance. The oil also has excellent anti-corrosion properties that help to protect engine components from rust and corrosion. Overall, Castrol Power1 4T 10W-50 Full Synthetic Motorcycle Oil is a premium lubricant that offers outstanding performance and protection for high-performance motorcycles. This oil is a great choice for riders who demand the best possible protection for their engines. Pros: Formulated with advanced synthetic base oils Castrol's proprietary Trizone Technology provides superior protection for the engine, clutch, and gearbox Shear-stable oil that maintains its viscosity under extreme conditions Excellent anti-wear properties Clean-burning oil that helps to reduce the build-up of deposits in the engine Excellent anti-corrosion properties Cons: None