I appreciate your help and you don't sound rude. I have done many searches and there is only about 10-15 messages on this topic with mixed opinions as to how wet clutch safe gear lubes are. I only count about 3-4 people who use Mobil 1 75w-90 in a Sportster (you being one). Harley would make this much easier if they listed a spec for the primary/transmission lube.

 

ssls6, i have an 07 883c and the owners manual says on page 36 use genuine harley davidson formula + transmission and primary chain case lubricant ( part no; 98851-05 quart) through clutch inspection cover opening,
cheers bretho.

 

Yes, the HD manuals will always tell you to use "genuine harley davidson" oils. They are pushing their overpriced products that when compared in dozens of authinticated lab tests don't measure up to the likes of Amsoil, Royal Purple, Mobile1 etc. HD oils are OK to run in your bike but even their Syn3 is made from a dino base.

 

Yes you can. The Harley Formula + is a gear lube (although they don't us what viscosity it is). Formula + is not synthetic, I recommend going synthetic in the crankshaft and the gearcase.

 

I found, in another forum, where someone recommended 20W-50 gear oil in the transmission.

I noticed no one here ever said what the oil weight was. I really don't care what Harley's part number is. I came here trying to find out what weight of oil to use in the transmission.

Here's my source:
http://www.buelletinboard.com/forums...ad.php?p=39215

Any comments?

 

I always put in Amsoil 20/50 motorcycle oil in both holes, it tells me to right on the bottle
Quote...High Performance Engine, Transmission, & Primary chaincase Lubricant...
So far I have 22000 miles on this stuff with no problems. Maybe I'm just lucky.

 

From what I recall based on UOA's, the 'moly' content of Mobil 1 75W90 Gear Lube is around 60 PPM, which is lower than many motorcycle specific oils that are designed to work with wet clutch operation. A moly content of 100 PPM or less is not enough to even worry about 'possible' clutch related problems down the road.

Most of the guys I know with Sportsters (including myself) have been running the GL-5 API rated Mobil 1 75W90 Gear Lube for many thousands of miles. As of a few months ago a Harley Dealership mechanic friend of mine had over 75,000 miles on his Sportster, and he has been running the 75W90 Gear Lube in his combination tranny/primary since day one.

Nobody has had any type of clutch related problems.

As far as moly content, the majority of guys I know that have the large single cylinder 'Thumpers' (such as the Suzuki DR650 and Kawasaki KLR650) use nothing but Mobil 1 15W50 in their bikes, which use a single oil for everything. Mobil 1 15W50 shows a moly content ranging from 60 to 90 ppm, and after many thousands of hard miles none of them have had any clutch problems.

Anyway, run whatever you want in the tranny/primary, but I prefer a good GL-5 API rated fluid, and Mobil 1 75W90 won't hurt anything in the least.

For those that that the 75W90 Gear Lube might be 'too thick' you need to remember that motor oil and gear lube are rated differently. A 75W90 gear lube actually has the same viscosity (thickness) as a 20W50 motor oil.

 

SuperTech full synthetic 75/145 GL5 keeps mine real quiet.

 

07 came with 20w50 dino in it. switched to HD synethic at 1K service in both cases. tranny/primary was noisey. Switched to royal purple at 5K. 85w140 in primary then. Tranny much quieter and no heavy clunking then, but royal purple really expensive. Switched over to Mobil1 75w90 in tranny at 10k. Same quietness in tranny, lube less expensive than royal purple lube. bike loves either, my wallet loves mobil1 more.

 

I changed from HD syn3 in both holes to Amsoil MCV 20/50 in eng, Amsoil severe gear 75/90 in trans. Bike runs much cooler (10 degrees cooler) and trans much quieter and shifts a lot better. Go to the Amsoil site and read about the oils. Their severe gear 75/90 is made for HD trans gears. Like cHarley said, the stealers are trying to push their oils, read Amsoil test results, compaired to other oils. HD does not tell you alot about their oils, except to use them. Hope this helps. Ride safe.