Researching service items for my 2013 FLHTC (Electra Glide Classic), I've been reading the forums and am seeing encouraging posts regarding Amsoil 20W-50 for motor oil and Bel-Ray Big Twin Transmission for the tranny. Have not seen anything yet on primary, though. What do y'all favor?

 

Don't put engine oil in your trany and primary... use real greabox oil, 75W140 is a good pick!

 

For your PRIMARY, use a PRIMARY fluid.

There are a number of them out there...

Harley Formula+ is not bad.
Drag Specialties makes one....

MY personal choice is Red Line Synthetic Primary Fluid.

I also prefer Mobil1 20w50 Vtwin for the engine, Amsoil is good, but M1 tests better on UOA's.

I like Amsoil 75w-110 for my transmission.

 

Redline , Bel-ray, and spectro all make primary fluid. I have used bel-ray and spectro both are very good.

 

I use the HD primary + in my twin cam.

It works fine.

other fluids also work...fine


the consideration is this:

on a fluid change about 38 oz will drain through the plug hole

leaving about 7 or 8 oz inside the primary- including soaked into the clutch disks

another type of fluid swapped in may not be compatible and clutch engagement may not be predictable.


that's why i stick with the same brand over and over

IF you want to get out all you can with out opening the primary, leave the bike on the jiffy overnight with the clutch lever pulled in with a zip tie.

every now and again, hit the starter to spin fluid out of the clutch basket

this will not remove any fluid absorbed into the clutch disks, but it will get almost all of the fluid out

FWIW i use the fluids as in the manual for all my bikes and cars- magic fluids will not correct a mechanical problem. fluid incompatibilities may mask or contribute to mechanical inconsistencies...such as a slipping or grabbing clutch

a "coloured" fluid can be useful is finding the source of a leak ( like the red tranny fluid in your car) so that can be handy

mike

 

Just switched from Harley fluids to redline...much better...I can till gears are noticaby smoother...much better...

 

Best Primary Fluid? There isn't one.

There are opinions.

Best Advice? SafetyMan already gave it to you.

For your PRIMARY, use a PRIMARY fluid.

 

Last change I put STP in it with 20-50. It shifts better. Think I will try mixing type F with the stp next time half & half. Used to run STP in metric bikes & have been using it in the motorl so far, so thought why not try it in primary as the metric clutchs liked it. The XS 650 was harder on oil than the hog. Alot of riders using in those bikes saprised I have not heard of anybody on here using it.

 

Yeah what he said...

 

If you change your oils like your suposed to it doesn't matter.
I did the redline shock proof for the tranny and wanted to throw up from the stench at a stop light in the heat with the smell rising up via the vent.