Preparing to switch to synthetic tranny fluid

[BD]

Hey all.

I have a 2002 WRX Wagon. Manual 5-speed. No modifications except a
grounding mod to help with acceleration hesitation between 3000-4000
rpm (negative terminal to intake manifold, negative terminal to right
front strut bolt).

There are a couple of persistent complaints I have about the tranny,
and I've done considerable digging both here and on NASIOC. Complaints
are:

-Chattering sound on deceleration, around the 3000rpm mark;
-First Gear Synchros, and the need to double-clutch when going from
second to first gear.

I've seen enough info to make me think it's time I flipped to Redline
Synthetic fluid. I'm at 60,000 kilometres now (I gather this kind of
change isn't recommended while the vehicle is still breaking in). I
called the dealer about the switch to synthetic, and they have no
warranty issues with doing so.

I've sourced out a vendor who can get the stuff here in Canada.

I gather I should use 75W90NS for the tranny, and 75W90 for the rear
diff. I'm not sure of the exact quantities of the fluids I should
order (the dealer doesn't stock it, so I'll be ordering it from
somewhere else and bringing it in with me, but I gather this info will
be in my user manual.

Is there anything important I've missed here, before I take the plunge
to synthetic tranny fluid?

Thanks,

BD

 

[Frank]

Hey all.

I have a 2002 WRX Wagon. Manual 5-speed. No modifications except a
grounding mod to help with acceleration hesitation between 3000-4000
rpm (negative terminal to intake manifold, negative terminal to right
front strut bolt).

There are a couple of persistent complaints I have about the tranny,
and I've done considerable digging both here and on NASIOC. Complaints
are:

-Chattering sound on deceleration, around the 3000rpm mark;
-First Gear Synchros, and the need to double-clutch when going from
second to first gear.

I've seen enough info to make me think it's time I flipped to Redline
Synthetic fluid. I'm at 60,000 kilometres now (I gather this kind of
change isn't recommended while the vehicle is still breaking in). I
called the dealer about the switch to synthetic, and they have no
warranty issues with doing so.

I've sourced out a vendor who can get the stuff here in Canada.

I gather I should use 75W90NS for the tranny, and 75W90 for the rear
diff. I'm not sure of the exact quantities of the fluids I should
order (the dealer doesn't stock it, so I'll be ordering it from
somewhere else and bringing it in with me, but I gather this info will
be in my user manual.

Is there anything important I've missed here, before I take the plunge
to synthetic tranny fluid?

Thanks,

BD

I have not done any looking into but I thought tranny fluid was all
synthetic. Wonder if this is a marketing ploy.
Frank

 

[BD]

I have not done any looking into but I thought tranny fluid was all
synthetic. Wonder if this is a marketing ploy.
Frank- Hide quoted text -

- Show quoted text -

Pretty sure there's a natural/mineral oil type, and a synthetic type.
Here's a blurb from Wiki: "Fully synthetic gear oils are also used in
many vehicles, and have a greater resistance to shear breakdown than
mineral oils. They can improve the shifting performance of "difficult"
gearboxes, where the excessive slipperiness of some mineral oils can
impede synchromesh action."

 

[Frank]

Pretty sure there's a natural/mineral oil type, and a synthetic type.
Here's a blurb from Wiki: "Fully synthetic gear oils are also used in
many vehicles, and have a greater resistance to shear breakdown than
mineral oils. They can improve the shifting performance of "difficult"
gearboxes, where the excessive slipperiness of some mineral oils can
impede synchromesh action."

You are most likely right. I did a quick search and found an MSDS for
a mineral oil base. As a retired chemist, it would be of interest to
me to see the precise chemistry laid out. I was probably also
thinking brake fluid which I believe is synthetic. This is reminding
me of an artcle in today's newspaper about Ferarri where in order to
maintain the warranty, you must use some super synthetic oil that will
cost about $720 per oil change.

Frank

 

[DS]

You can get all your fluid quantities from your manual. It will also
indicate what grade of fluid is required (ie 75W90, GL-4, GL-5).
I'm not sure if your WRX has a rear LSD, but that will make a difference on
what fluid you need. Doesn't Redline's website tell you what fluid to use
based on the year make and model?

Anyway, you'll be happy with Redline fluids. They made a huge difference for
shifting in all my higher performance cars. Shifting in winter is much
improved too.

DS

 

[BD]

Doesn't Redline's website tell you what fluid to use

based on the year make and model?

Dunno. Haven't checked there. I've been on this forum, and the NASIOC
forums, working off anecdotal information. Some of this anecdotal
information includes recipes for cocktails of different manufacturers
fluids. Probably void any warranty by going that route, but apparently
it works for some.

Anyway, you'll be happy with Redline fluids. They made a huge difference for
shifting in all my higher performance cars. Shifting in winter is much
improved too.

I hope so. I'm seeing some reports that it makes a difference, and
some that it won't change things one iota. I expect that the change in
fluids would help with some problems, but not necessarily all. I also
gather that it should make a big difference right away, but after
about running it in for awhile I should expect to see the old issues
creep back over time. I dunno. We shall see.