Synthetic ATF

IMHO, you should be referring to car's manufacures recommendations.

later,

tom @

What the HELL is a Picnic??? ;) I used to know, can't remember...

Have you been keeping up with regular tranny sauce changes; is the fluid the proper colour, not smell burnt; have you flushed the tranny at all?

This would require a complete flush and refill of the tranny. You didn't say how many miles. If it is over 60,000 miles, I wouldn't even bother. Just keep using what you're using.

We have flushed 3 cars with over 100,000 miles; in all three cases, the tranny has dropped dead within 250 miles of the flush.

I've put the Mobil 1 ATF in my Saturn (go ahead and laugh) that suffered from a notorious hard shifting (slamming) problem. Where regular ATF made no difference, the Mobil1 significantly improved the shifting. I drive hard and also pull it 4-down behind an RV, so it gets the worst of both worlds, and the Mobil1 is lasting longer before needing changed.

Steve

Mobil1 is fully compatible with standard ATFs, so you wouldn't have to do a complete flush. Just like when switching to synthetic motor oil, synthetic ATF has different flow and detergent properties, so you will likely knock loose some existing gunk; a second drain-and-fill shortly after the initial switch would probably be a wise investment.

Steve

That was probably because you did not do a proper flush, just a drain and refill.. New fluid needs to run through the tranny and converter with a flushing machine to clean out all the gunk before refilling.

mike hunt

hachiroku wrote:

hachiroku wrote: snip.

And I've never flushed one in my life...I've likely owned 12 - 15 cars, haven't driven a lot I'd say, and only had one transmission fail, don't remember ever having any trouble in that respect at all (other than that one). So I'll take your advice Hachi...

Yeah, we haven't had a lot of luck with complete flushes, and even a lot of techs I know say unless you have religiously maintaned the tranny, don't do it. About 3 months ago I posted a dissertation about why I think it 'don't' work; basically, you've removed all the friction and the worn parts can't grab anything.

Yeah, I've heard that too, just keep doing drain and fills until it's mostly synthetic. I have also been told that it IS compatible with existing ATF's, so you can just add it as you would whatever you're using now.

I started using it in our '98 Sienna after the first change at about 10K. As long as the fluid specified for your car is a Dextron type, the Mobil 1 should work fine. We noticed smoother shifting right away and at 115K miles currently on the vehicle it still shifts like new. I've drained and refilled ever 25K including changing the filter screen at 100K. As additional insurance I also fitted a transmission cooler.

Hmm my turn huh?

Here's my brief two cents:

compared to how motor oil, how often would you replace the ATF? I think it's worth the extra cost.

dave

Jeff Bertrand Wrote:

My wife has just bought the car as a runabout. The service book is all stamped up.

I did, I said 64,000

So, it is best to use normal ATF, and then drop that after 300 miles or so then use fully synthetic ATF, rather than a flush and then fully synthetic ATF? Is that what you are saying?

??? Huh?

So, just drop the oil and replace with fully synthetic ATF?

It is.

The book specifies 27,000 ATF changes. At 64,000 miles I was thinking that fully synthetic ATF will prolong the transmisison.

A waste of money. Not that Mobile one ATF is a bad product but I have rn a few auto trannies past 200k with regular fluid with a aux cooler and regular changes too. You could argue that syn ATF fluid take heat better but the problem when it gets hot is not just the fluid, it is the seals in tranny too and so if your SYN ATF can take 300 degrees no sweat, your seals cannot and it will greatly shorten their life. Keep tranny cool (around 180 to 200F) and change fluid and filter every 30K or so depending on usage and you should have a long service life. Heat is trannies number one enemy, control it and you extend its life. The only possible advantage I could see to full SYN ATF would be if you lived where it got to be 40 or 50 below in winter ans it would pump better in cold weather but I lived a while in a place like that and I used to add about 16 to 32 oz of kerosene to my tranny (depending on size) in winter and they worked okay too and the kero would evaporate out during the warmer months. BTW both of those vehcials I did that to I still own and 10 years later they still work fine (one was pretty new at the time too). THere is one thing that I do use Mobile SYN ATF in regularly, I use it in my snow plow hydrualic systems and it does flow better when it get to around zero and below as plows do not heat the oil much unlike a tranny.

It is very expensive and not worth the cost. As I said early I have seen a lot of 200k mile trannies on regualr oil and while syn ATF can take a lot more heat than regualer ATF, The seals in the tranny cannot so the extra temp stabilty is of no real value. Use regular ATF and keep tranny cool and it will last just as long without SYN. I might also add to that unless you either dismantle and drain tranny completely or power flush it, you will have a lot of regular ATF in it still after a regular filter and fluid change. (it is not like a engine oil change were most of the oil comes out)

What is "a Dextron type" and is that compatible with what is specified for the Toyota transmission?

Huw Hint, maybe you mean 'Dexron'?

No. Synthetic ATF is meant for units like Mercedes, GM and ZF which are effectively 'sealed for life'. However the fluid only holds specification for maybe 100,000 to 120,000 miles but even when it goes out of spec the tranny will likely live for quite a while longer.

Is it noisy to start with? Probably not or marginally would be my answer.

Very long oil service life. Higher margin for oil company if regularly changed. Low service cost for vehicle owner if matched with transmission designed to be zero maintenance with built-in durability and reliability.

Huw

Typically only about one third of the total oil is drained from an automatic transmission. The aim of draining is not to replace dirty oil with clean, as in an engine, but to regularly top up the friction modifiers and detergents to an acceptable level. The advantage of synthetic is that these properties do not degrade even after an extended period.

Huw