Transaxle Oil Analysis

[bwilson4web]

Hi Dave,

Originally Posted by whodat

. . .
Does anyone know how the transaxle oil breakdown changes with frequency of cold starts versus continous freeway driving?

Does continous freeway driving (presumably at an elevated temperature) break down the transaxle oil lubrication properties faster than more frequent temperature changes in the oil with short frequent trips?

I'm at 60K miles and my commute is 100 miles roundtrip. From data presented it would seem that doing a transaxle oil change soon would be a good idea. However, its an expensive service item.

We only have a limited number of samples and some informal observations from highway driving. Near as I can tell, the only correlation that we know about is "dusty" environments -> higher silicon/aluminum contamination. In 100F weather at 70+ mph, I'm seeing MG1/MG2 temperatures climb to 100C. This is getting in the range of hot oil but not excessively so.

I have some other ideas that are associated with aeration but nothing to publish, yet. It is possible that the differential gears may be aerating the oil and this can lead to micro-dieseling effects. Higher speeds would only compound the problem. There may be nothing we can do about this but know it is one of the aging mechanisms and use testing to determine when the oil should be replaced.

Bob Wilson

[dogfriend]

Originally Posted by whodat

I'm at 60K miles and my commute is 100 miles roundtrip. From data presented it would seem that doing a transaxle oil change soon would be a good idea. However, its an expensive service item.

Thanks
Dave

This is a fairly easy DIY service if you have the capability to do your own work. You need 4 qts of WS ATF (I bought it for $5.20 / qt) and two aluminum washers for the drain and fill ports (about $0.80 each).

I would think you could get this done for about $50 - 75 (about 30 min labor). Maybe an independent shop if the dealer wants too much.

[whodat]

Originally Posted by bwilson4web

Hi Dave,

We only have a limited number of samples and some informal observations from highway driving. Near as I can tell, the only correlation that we know about is "dusty" environments -> higher silicon/aluminum contamination. In 100F weather at 70+ mph, I'm seeing MG1/MG2 temperatures climb to 100C. This is getting in the range of hot oil but not excessively so.

I have some other ideas that are associated with aeration but nothing to publish, yet. It is possible that the differential gears may be aerating the oil and this can lead to micro-dieseling effects. Higher speeds would only compound the problem. There may be nothing we can do about this but know it is one of the aging mechanisms and use testing to determine when the oil should be replaced.

Bob Wilson

Hi Bob,
Thanks for sharing the data on your website. Good to know that higher speeds compound the problem. Yet another reason to drive slower (and get the better mileage).

I understand that air friction is proportional to the velocity squared. I wonder whether this is true for lubrication friction (being proportional to the velocity squared or linear with velocity)?

Thanks
Dave

[whodat]

Originally Posted by dogfriend

This is a fairly easy DIY service if you have the capability to do your own work. You need 4 qts of WS ATF (I bought it for $5.20 / qt) and two aluminum washers for the drain and fill ports (about $0.80 each).

I would think you could get this done for about $50 - 75 (about 30 min labor). Maybe an independent shop if the dealer wants too much.

In California, the Santa Cruz dealer is quoting about $200. One hour of labor plus the cost of the fluid. To drain and refill.

I asked the dealer if the pan could be dropped and wiped clean, and they want an additional 3 hours, which would then be in the $450 range.

For those who have done this service, did anyone ask for the pan to be removed and cleaned and if so what metal shaving/sludge was found?
Thanks
Dave

[Patrick Wong]

Originally Posted by whodat

I asked the dealer if the pan could be dropped and wiped clean, and they want an additional 3 hours, which would then be in the $450 range.

For those who have done this service, did anyone ask for the pan to be removed and cleaned and if so what metal shaving/sludge was found?

Since you own a 2G, there is no drain pan to be dropped. The magnet on the drain plug needs to be wiped off, there probably won't be much accumulation of ferrous powder on it.

You need 4 qts of Toyota ATF WS which should cost ~$20 plus two new aluminum washers which should cost $3. So if your dealer wants $200 the labor rate must be unusually high! Might be worth your while to learn to DIY.

Classic owners will find significant powder debris on the magnet and if the transaxle is in bad shape, the magnet will look like a bad hair day. I've done this transaxle oil change on both of my Prius.

[dogfriend]

Originally Posted by whodat

In California, the Santa Cruz dealer is quoting about $200. One hour of labor plus the cost of the fluid. To drain and refill.

I did this myself in less than 30 minutes including taking a sample for analysis. It requires about the same effort and skill needed to perform an engine oil change. So I think the amount your dealer quoted is way high.

Patrick is correct - there is no pan on the 2G (2004 -08). There is a magnetic drain plug. I had a lot of grey metallic (Fe) debris at 9562 miles. The ATF was still red, but much darker than new WS ATF.

[whodat]

What's the best oil to use for the transaxle? Is there an equivalent synthetic oil like Mobile 1 5w-30 for the transaxle?

Thanks
Dave

[galaxee]

we're doing this at 50k for the simple reason that we have the fluid and now it's taking up space we wouldn't mind having back, as opposed to residing on a shelf in DH's work area where space wasn't an issue. :P

anyone collecting samples? i can't pay for an oil analysis as things stand right now, but i'll ship to anyone who really wants it.

we're currently just over 47k (um, maybe 48k, i forget) so it will probably be done next month or early may.

[dogfriend]

Originally Posted by whodat

What's the best oil to use for the transaxle? Is there an equivalent synthetic oil like Mobile 1 5w-30 for the transaxle?

Thanks
Dave

I think its probably best to stay with WS ATF for the 2004 -08 transaxle. Some of us believe that the dielectric properties of the fluid could be important as well, but there is no definitive proof one way or the other. It is probably best to use WS for warranty coverage as well.

[JimboK]

Originally Posted by galaxee

anyone collecting samples? i can't pay for an oil analysis as things stand right now, but i'll ship to anyone who really wants it.

I think Bob Wilson is.