Anyone have any issues running HD SYN-3 oil in the engine, trans, and primary? I have been now for a season and am getting ready to switch back to the original recipe.

 

Always used Amsoil products in my FXRS.

 

Gear oil in the transmission. (I use Amsoil also)

 

I had to switch to Syn-3 in the primary because the regular Harley dino stuff was no longer available. I've developed a 'whirling' noise about 500 miles after the swap. Don't know if it's from the oil or not. I might try something different the next scheduled change.

For the transmission I'm nowusing Mobil 1 gear oil (same deal, couldn't find the HD semi-syn). I don't really notice a difference from the stock HD semi-syn oil I used prior. But then, my 93 doesn't have any backcut gears, so it's rather noisey anyway. (I laugh everytime I read about the 07's with the 'noisey 5th gear'-hell the day I rode my 93 FLHShome from the dealer I thought I was in my old Peterbilt)

 

My 98 FXSTC has had syn 3 in all three holes since it was new. With almost 50,000 miles, I changed to Mobil 1 oil and transmission lube (I have dyno oil in the primary). I have noticed a considerable difference (positive) in the way it shifts.

 

I use regular 20w50 for summer months. HD360, TwinPower, Revtec, Castrol GTX, and other various aftermarket oils. Currently, it is has Valvoline VR1 and that is a pretty good oil.

The winter months...it gets 15w40 diesel oil. Rotella, Motorcraft, and other storebrand diesel oil.

The primary gets 15w40 diesel oil year round. I don't care who makes it.

The transmission gets 80w90 GL5. It has been regular, synthetic, and semi-synthetic. I don't care who makes this stuff either.

Absolutely no trouble and this way works for me.

 

I've been using Harley 20W/50 dino in the crankcase. Formula + in the primary. Just switched to Mobil 1 75W/140 in the tranny. The Mobil 1 made a huge difference. Really quieted the tranny down. Sixth gear is almost quiet now.(aftermarket)

 

Why do you use diesel oil?