What's the best manual transmission oil?

[paulwelkins]

I just bought an HF transmission for my CRX and the installer is recommending 10/30 weight saying it will cause a little less in mileage savings but better for gears. And he says not to use any synthetics. Does anybody have a suggestion?

[MetroMPG]

Did he say why he didn't recommend synth?

Synthetics actually make more sense in drivetrain components (vs. engine) because they don't benefit from the heat of combustion to warm the oil & allow it to flow more easily. Synth fluids have more stable viscosities in cold conditions than mineral oils.

If you live somewhere that experiences cold weather, I would say the lightest weight, synthetic oil you can safely use in the transmission is what to go for.

The installer by definition sees lots of gearboxes that are damaged by hard use and neglect, and that probably colours his lubrication recommendations.

[Daox]

I'd use the lightest weight that the manufacturer recommends, in a synthetic brand such as Redline, Royal Purple, or Amsoil.

[dremd]

I don't know what oil is specified, but 10-30 weight is way way to thin for most transmissions.
I've used Redline MTL (90wt) in several boxes and noticed longer coast distances than whatever was in them prior.

Many manual Transmissions use ATF, I've never swapped fluid in one of those. . . .

Vw uses a special oil which has a lower viscosity than most in (some) of their boxes it is called G52 http://forums.tdiclub.com/showthread.php?t=132884

Good luck.

[MetroMPG]

The oil in my transmission (GM Syncromesh semi-synth) is closest in weight to 5w30 motor oil based on a comparison I did by pouring the same volume of each through a cotton filter and timing it. I don't know if that's a valid comparison of viscosity or not.

[dremd]

ATF and Gm Syncromesh are very similar products.

Many Vette, Mustang guys run ATF for one reason or another and their transmissions require Syncromesh.

[jazzie604]

hondas DO call for 10w30 oil. Just the way they were designed :whoknows:

[diesel_john]

the vw spec's 90 wt, and i use John Deere trans. oil, which is hydraulic oil. We'll see how long she lasts. been using it a year now.

[Ryland]

some people sware by the MTF that Honda sells, it's about $30 to fill your tranny with it, but it will not hurt it at all, and is most likely slightly better then 10W30, I currently have amsoil 5w30 Manual Transmition Fluid in my honda for the past year (20,000) and it's working fine, but whatever you do, don't put gear oil in a honda tranny, the sulpher compunds that act as a high presure lube will destroy your bushings.

[DAN]

the honda oil maybe Synthetic. some hi-po cars come that way. if you raceing and don't mind re builds l us lighter oil. if not do what honda says.