I've been a member here for a little over a year now. I've learned a lot in that year.
I don't recall
recommending Mobil 1 15W50 redcap in the primary--but I did use that oil in my primary and did not have any problems with it.
As sunruh says, Mobil changed the color of the cap on the jug and increased the price of the oil. It would be nice to think that they made the oil better, but VOA's don't indicate any better additive pack, so we'd have to take Mobil's word for it that the base is actually better. XOM has been sued for selling the same oil in different bottles at different prices (it seems that the Mobil Drive Clean and Exxon SuperFlo were the same oils, but XOM billed the Drive Clean as a better performing oil and charged a commensurately higher price for it). So I cannot give XOM the benefit of the doubt on the "improved formula" for the new Mobil 1 15W50. Sorry.
If I do say so myself, I have the two best UOA's on the board on a Harley Davidson engine--and the oil is Havoline 20W50 dino oil. You'll find my post in the Motorcycle UOA's.
Since you're changing the oil every 2500 miles--which I think is wise because you can get fuel dilution issues with these engines--I would not waste money on a synthetic. The Havoline is about 1.50 per quart, and I defy
anyone to post a better UOA with a syn in an HD engine than I achieved with Havoline dino.
For the primary, Shell Rotella 15W40 is hard to beat at about 1.75 per quart. That oil is tough as nails and you can find it all over the place. Harley even recommends diesel oils when you can't find their stuff. Or you could use Castrol GTX 10W40 since it, like the Rotella, has hardly any moly to speak of. The Rotella is moly free, and the GTX has less than 50 ppm. Some believe that moly can cause excess clutch wear because of initial slipping. Since I don't want to burn a clutch proving them wrong I've just stayed away from moly oils in my primary.
That said, I did not feel any slipping of my clutch when I had the Mobil 1 15W50 in there, and it had about 75 to 100 ppm of moly in it. But just because you don't feel a slip, that doesn't mean that some slipping isn't occurring.
I agree with the Mobil 1 75W90 in the tranny. It's a good gear oil and I found that my shifting improved 100 percent over the Harley Semi-Syn transmission lube.
You can run Rotella in the primary and Mobil 1 75W90 in the tranny for 5K without any concerns whatsoever. If the original Harley lubes can last 10,000 miles in these locations, 5K would be a cake-walk for the Rotella and Mobil 1...
So just change the engine oil every 2500 miles on a "short service" and do all three every other time (long service).
I don't think you could want a better engine oil than the Havoline 20W50 SL rated oil. (And it's still SL in the 20W50 grade).
If you have lots of money, the Mobil 1 20W50 can serve you very well for the short intervals you plan on using, but at around 8 dollars a quart I would rather use the Havoline and spend the money I saved on a UOA at 2500 miles--which should prove to you that the Havoline is up to the task.
Dan
