I'm going to change my tranny fluid. Currently has Pepto Bismol (Redline Shock Proof Heavy), and I want to put Spectro 6-Speed tranny fluid. But I want to flush out the Pepto before putting in the Spectro. By "flush", I simply mean draining the Pepto out, filling back up with a cheap fluid, running it through the gears for a minute or two, and then dumping it out again.

My question is, what is the cheapest fluid that I can use to "flush" it with? Can I just pour in a quart of 50w motor oil? Just want to make sure that whatever I put in won't do any damage for that few minutes of flushing.

 

I would think that the residual amount of Redline is more compatible with the Spectro than any other cheap oil you could run in there to flush.

 

+1 on HarleyWood's remarks. Any gear oil should be compatible with any other gear oil.

 

Hmmm...didn't think of it that way. Excellent point!

 

Drain the old fluid right after a ride (when the trans is warm) and you will minimize the amount left in there to mix with the new.

 

I was thinking that... but I was also thinking that it may be best to drain it after it's been sitting all day/night because all the fluid is in the bottom of the pan already...

 

A flush isn't necessary, but if you would feel better about it use any inexpensive gear oil. Drain while the oil is still warm to get most of it out. There will still be pockets that don't drain (not all the oil drops to the bottom), so it would take a few flushes to get the majority of the old oil out. Mixin' the two oils will only stain the new with a little of the pink stuff. Of course then your new special oil will be mixed with the inexpensive stuff..........

 

Just curious why are you changing?

I used it in my Dyna for years and it was great stuff. I had a leak in one of the tranny seals. It showed up as a leak on my jiffy stand. Because the leak had a slight pink color to it I knew it wasn't just primary oil.

 

It's time to change it, and I just want to try something different. Nothing wrong with the Redline SPH though... Seems that everyone on this forum highly regards it (thus why its in there now), but everyone at HDtalking.com seems to highly regard the Spectro stuff. Just thought I'd try it to see if I notice any difference. Highly doubt I will though.

 

I would say if you want to get it all out, just run it until it is warm, pull the plug ,then let it drain all night long. There is such a small difference in gear synthetic oils, it would be impossible to tell a difference from one or the other simply by running the bike.