Originally Posted By: GMBoy
Originally Posted By: dnewton3
Originally Posted By: yankees1
I will soon take delivery of a 2018 Fat Boy and after I reach the 1000 mile mark I will need to decide if I want to use the Harley synthetic or use Amsoil synthetic motorcycle oil. Of course I am receiving pressure from the Harley salesman to use their oil . Thoughts ?
Pressure from HD to use their products, eh? Kindly remind them that they must provide their branded products FREE OF CHARGE (per the M/M Warranty Act) if they are to insist for the purposes of warranty coverage. Otherwise you may use any brand that "meets/exceeds" their specs. And if they don't publish those specs for the aftermarket, then you are free to use what you see fit.
https://www.ftc.gov/tips-advice/business-center/guidance/businesspersons-guide-federal-warranty-law
See "tie in sales about a third of the way down.
I vote for Rotella T4 in 15w-40, but it sounds like you're on the "syn" bandwagon. I'm not a fan of T6; shears too much in bikes. (I understand your engine isn't a shared-sump bike, but T6 just does not return performance for the dollar IMO. T4 does every bit as good for far less cost).
The issue I see with your recommendation is that HD calls for 20w/50. I know a few folks running 15W/40 HDEO just as you recommend with good results but maybe he should stick to 20W/50 while under warranty.
Yes that point is valid. Even if a manufacturer doesn't list every detail of the oil they "require" you will need to meet the ones they do make known such as the "correct" viscosity to avoid the warranty from being voided. (at least the 50 part anyway. I suspect they would have a very hard time arguing that the 20W offers any critical performance benefit over a 15W or 10W).