unhappy with 80w-90 gear oil

[dlb]

i've put traditional 80w-90 gear oil in all of my tercs and my 4wd corolla. each of these cars has had at least one gear with worn synchros. those gears all shift more or less fine once the car has been running for 5-10 minutes but while the car is still cold, shifting into them is a pain. i'd like to try some gear oil that is thinner when cold to improve this.

so, does anyone have any experience with something that lubricates worn synchros adequately even when cold? i am open to both traditional and synthetic oils. i'm not looking for anything to magically fix worn synchros, i just want them to shift adequately when cold, like they do once 80w-90 has warmed up.

[Gottolovem]

I have the same issue I think that Petros has posted in the past that he likes a mix of reg and synthetic.
Not sure what weight or ratio is the best perhaps he can chime in ?

[dlb]

i know that both splatterdog and 4wdchico use full synthetic. 4wdchico uses stuff marked 'NS' which indicates it does not have friction modifiers for limited slip diffs (i think), and i'm not sure what splatterdog runs. i'm hoping both of them see this thread and comment on how their choices of gear oil act in cold weather.

[MR2Di4]

I was experiencing the same problem with my Trans when I did a fresh fill. I found that draining oit half of the new 80W/90 and replacing it with a broad range full synthetic yielded good results. The only hard shift is the 1-2 shift on cold mornings, but after a couple of miles everything seems to work just fine.

MR2Di4

[dlb]

...replacing it with a broad range full synthetic yielded good results.

sorry mr2di4, what do you mean by "broad range"?

The only hard shift is the 1-2 shift on cold mornings, but after a couple of miles everything seems to work just fine.

is that with the synthetic/traditional mix? that's what i'm currently experiencing with just 80w-90 traditional oil.

[Petros]

the syncro works by friction, slipperly oil like synthetic will reduce friction and reduce the syncro's ablity to work properly.

this is why they do not work well when cold, the oil is thick. Once it warms up it is thins and is less slippery, so the syncro works properly.

ATF is designed to allow the auto trans clutches to grip, running perhaps 20 percent ATF with the regular multi vis gear oil might help. I do not know the long term consequences of doing that. We ran a 50/50 mix ATF/gear oil mix in the Nissan race cars to allow faster shifting. the trans held up well to racing abuse (hard fast shifts at 10,000 rpms), and the trans was more or less similar to the production trans except for closer gear ratios. When I asked my boss at Nissan about running a 50/50 mix for street use he sternly warned me that I should use what the trans was designed to use for daily driving.

You might try running 50/50 mix for a week or so and than changing it out with a lower viscosity gear oil. that will flush out sludge and deposits out of the syncros, and give lower viscoity oil a better chance to grip.

[MR2Di4]

...replacing it with a broad range full synthetic yielded good results.

sorry mr2di4, what do you mean by "broad range"?

The only hard shift is the 1-2 shift on cold mornings, but after a couple of miles everything seems to work just fine.

is that with the synthetic/traditional mix? that's what i'm currently experiencing with just 80w-90 traditional oil.

For whatever reason the Valvoline full synth said 75W/140 on the bottle which I took to mean it would work with a "broad range" of temp and viscosity requirements.

Yeah that's with the mix, but it was a lot more pronounced with just straight oil. At least now I can make a reasonably smooth shift if I don't wind it up on cold mornings.

[TURTCEL]

I just added a bottle of LUCAS Trans fix to my Terc since 3rd gear has been a little rough shifting into...we will see. Might be too thick but can be changed.

Peace

[c_j]

For the record, I was running full synth (Castrol or Mobil1 75w90 )in my last Terc (worked nicely), and my current one had synth in it when I got it and it shifted wonderfully. Now I've got regular gear oil in. With the regular gear oil and the colder temps, shifting is a great pain from 1 to 2 and also 2 to 3 until things get warmed up.

I would go back to synthetic.

[dlb]

that's really interesting, colin. your current terc shifted fine when cold with synthetic, and shifts lousy when cold with traditional? if it is that black and white for you, i may give synthetic a shot.

[c_j]

that's really interesting, colin. your current terc shifted fine when cold with synthetic, and shifts lousy when cold with traditional? if it is that black and white for you, i may give synthetic a shot.

Not quite. I have not had the synthetic in the cold temps (with this trans). I should have made separate statements there:

• The trans shifted better with the synthetic 75w90 (warmer temps).
• With regular 80w90 the cold temps, the trans upshifts really poorly, especially when cold and more so in the lower gears.

[Petros]

when I changed from gear oil to full synthetic (purple MTF) with my current high mileage transmission, it started leaking gear oil out the seals and the regular gear shifts were clashing gears like the syncros were suddenly worn out. After enough of the purple MTF leaked out I put back in about half regular gear oil, with about half purple. The seepage and gear clashing subsided.

last gear oil change I used 3 quarts of Valvoline multi vis gear oil and one quart full synthetic. shifting is slow when stone cold on really cold days, but otherwise good all other times. I double clutch it to down shift when the trans is still cold.

[Mr. Mad Ox]

Petros, are you talking about this stuff:http://www.amazon.com/Royal-Purple-Sync ... hromax+mtf or this stuff: http://www.amazon.com/Royal-Purple-Perf ... sim_auto_1

I think I'm having a similar issue

[atoyta]

I have had good luck with the redline synthetic mtl

[Petros]

yes, that is the stuff, "Royal Purple MTF". costly too (about $60 to fill a T4wd transaxle). I felt stupid after paying that much to have it leak out and make my trans act like the syncros were worn out.

most of the stuff labeled "synthetic" are actually blends, which might behave better than pure synthetic. A lower mileage trans, or a fresh rebuild with new seals and syncros might also take to pure synthetic gear oil better than a worn one.