Originally Posted by
rick130
In my experience I found Redline to give a slightly notchier upshift compared to Syntrans in the R380.
I always double de clutch/heel and toe down shifts so can't compare.
In the Patrol gearbox MT90 and Syntrax 75w90 were indistinguishable in characteristics, up and down.
I'd happily run whatever was easier/cheaper to get.
I used to find 20,000 km was the absolute limit of Syntrans, it would start to shear around that point and shift characteristics would deteriorate.
John, bush65 found the same.
This doesn't happen with Gear 300, but I'm not an advocate of extended drains on gearboxes as the contaminant levels rise, (no, or only rudimentary filtration) and the R380 only has a relatively limited oil capacity compared to, say, the big Patrol box or even my partners little Ford Courier. (Sadly she had to give back the TD5 130 she used to drive when she left the family farm)
Gearboxes are hell on fluids and shearing is common, and engine oils in gearbox use experience this much more rapidly.
It's really surprising with Syntrans as it's a Castrol Germany designed fluid, fully synthetic (POA's and esters) and I'm pretty sure it uses some pretty clever viscosity index improvers that mimic base oils and so resist shear, but what I think it does is illustrate how demanding a simple gearbox application can be.
Texaco's MTF94 was a really good fluid for cooler climates but it also only has a limited life being a syn fortified mineral oil and it's been unobtanium here for long time.
Redline MTL was an excellent replacement but I preferred Syntrans, cheaper and at the time, easier to get, but Pat303 had been running it for years in his Tdi and loves it, and I think that car has over 400,000km now.
I remember JC mentioning one day how idiosyncratic the LT77 and R380 can be, as some of his customer cars still shift better with ATF.