That's Redline Shockproof for sure. How did it shift before you checked it?

Lightweight Shockproof is recommended by some in the Sportster, I think color may be the same.
You may want to do some research before flushing that stuff out.

 

It could also be Red Line Primary oil , a lot thinner than the Red Line gear/trans oil.

Update:Sorry,just saw pics, thats RL Heavy Shockproof

 

Some guys run this stuff in AZ in the summer cause it thins out some with all the heat. Flush it out with a few changes....

 

OOPS, My dial up connection is so slow that the pics just came up. Thats RL Heavy Shockproof fo sure, i use it in all my twin cam trannys. Great in the twin cam trannys but not for Sporty primary/trans. That stuff is misserable to flush out, good luck.

 

If I remember correctly, Redline's MTL or Primary oil looks like normal oil, not the signature Pepto Bismol red. I never use any of Redline's Shockproof oils other than "Heavy", so Cromagnon could be correct that it may be Lightweight Shockproof, either way I would still change it as you probably don't know how old it is and you'll know exactly what you'll be putting in vs. guessing...

 

I too bought a bike with red oil in the primary(09 XR1200). It had only been in there for a 100 miles past the 1000 mile service. Wasn't thick like that and i changed it out as soon as i saw it, to Mobil 1 75/90 gear oil. Works great.

 

That's Redline Heavyweight Shockproof. I've tried it, and the Lightweight Shockproof, which is blue. Both were OK, clutch worked fine, but shifting was a little clunky with both. I've tried Mobil 1 75w90, which also works about the same as the Redlines.

I have been trying different stuff, just to see what seems the quietest. I now have Valvoline Durablend 80w90 gear oil running , and it's been the best overall for smooth clutch engagement and 'snap instead of clunk' shifts. Maybe the combo synthetic and dino is the best of both worlds. About half the price of full synthetics too.

Next motor oil change, I'm trying the Valvoline 4T 20w50 motorcycle synthetic that's now at Walmart for $7.99 quart.

 

Thats why I corrected myself in post #14
The Red Line Synthetic Primary oil is red or could be called a red tint, otherwise it looks and pours just like motor oil, dont know about MLT

 

Must have missed #14, sorry. MTL or Manual Transmission Lube is also made by Redline and is the same product as their Primary lube in a different package.