Ok, so I got the 1997 FLHTCUI. I serviced it this time with Harley conventional 20w50 and Formula Plus in primary and tranny.

I have been told that I should try the following:

Engine - any good conventional 20w50 motorcycle oil
Primary - 10w40 conventional motorcycle oil
Tranny - 75w90 Synthetic year oil

All thoughts are appreciated. The only one that concerns me is the synthetic gear oil in the tranny. Some say yes and some say no way.

 

I personally avoid Hypoid/synthetic... and use about any Cheap *** 10w30 in the primary... Synthetic Blends [motorcycle specific] seem fine for the 20/50
or straight weights in older stuff... [I consider the late '90's as "New"]

 

I use synthetic ATF in the primary. I currently have Mobil SHC630 in my tranny, but will probably go to whatever Redline recommends for it when I run out of SHC630.

 

I swapped to synthetics after 10k miles on my ‘97 FLHR, way back in ‘99. I’ve been over 90k since without any issues.

Mobil 1 15-50
Redline MTL in the primary
Redline Heavy Shockproof in the transmission

I used HD 20-50 for an oil change once on road trip... it stayed cleaner looking a lot longer than the Mobil 1. Made me wonder where the contaminates went!

 

Lubrication is overrated, just change it as per manual, your engine doesn’t know what kind of oil it’s using.

 

Agree with above except I go with Walmart 20W-50 automotive in the primary at $2.59 / qt (Cause it's accessible and cheap (165,000 miles.))

 

I have heard that some Evo riders in hot climates use 60 weight dino oil. Because it lessens engine noise. I switched from Amsoil 20-50 to Amsoil 60 weight. I may try 60 weight dino oil next oil change.

 

20w50 is all any Evo needs.

No reason to dump SAE 60 oil into an Evo...

But some people would use SAE 70 if they could find it.

 

20-50 Dino oil in the engine, whatever is the cheapest in the primary, and Redline shockproof in the trans.

 

I’ve started using Mystic semi-synthetic 15w50 by the gallon at a Atwood’s store 10-$12. If not that....cheapest 20w50 I can find. A few winters.....I’ve run diesel 15w40, but never in the summer. Several years ago.....I rode out in Arizona & New Mexico.....ran 25w60 in really hot weather.

Primary.....I like diesel 15w40. I liked ATF fluid, but it always found the weakest part of the gasket seeped out. Whatever you use...avoid the conservation energy....ones with the star on them. Or your clutch might start slipping.

Transmission....just use gear oil. 80w90