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Automatic transmission fluid

Hi all,

Recently acquired a Rover 416 auto, which I'm planning on servicing in the next couple of weeks. As part of this, I think I shall change the fluid in the autobox, as although it looks clean, I don't know when it was last done.

Now, I know very, very little about automatic gearboxes, other than that they're very, very complicated (have you seen the scary pictures of the inside of one on howstuffworks.com?), and that one shouldn't argue with them.

However, the book-of-words proclaims that it should be filled with fluid meeting the 'Dexron II' spec (I originally read that as 'Dexter II', and wondered what Dexter junior has to do with my gearbox). A browse through the shelf in Halfords, however, only gave me the option of Ford auto fluid (which is apparently a law unto itself), and Dexron III fluid.

Given that when I drain it, a load of fluid will remain in the torque convertor and therefore have to mix with the new fluid, can I just use Dexron III fluid, and will it mix happily with the presumably Dexron II fluid that's already in there? I'm assuming that these Dexron specs work like DOT classifications for brake fluid, and I can just mix III with II...

Cheers,

Brian.

Reply to
Brian Ruth
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ATF doesn't deteriorate in use, and doesn't need changing, as long as it looks a nice healthy red, it will be fine.

The only time you need to change it is if it has turned black, which is caused by the brake bands inside the gearbox slipping, and is generally considered a sign of a fsked gearbox.

Reply to
SimonJ

I did wonder about that, actually - my Haynes Renault manual refers to a Renault autobox which is 'sealed for life', and cannot be refilled. Even the version which can apparently needs a special Renault machine just to check the fluid level.

However, the Rover service schedule does appear to specify an ATF change at 60,000. This car hasn't done that milage, but I can't tell when it was last done, so it's possibly more than 5 years ago.

I found a bottle of ATF in a relative's garage which is a sort of cherry-red colour. The stuff in my gearbox is nice and clear, but looks rather paler to me - sort of pinkish, unless that's just because I'm only looking at a small sample on the dipstick. Does this stuff oxidise over time...?

Brian.

Reply to
Brian Ruth

What a load of cobblers!

The easiest way, if alittle wasteful is to identify the flow and return on the trans cooler, disconnect the return at the box and direct it into a largeish can. Have an assistant ready with 5 litres of fluid, a funnel and the filler open ontop of the 'box. With the box warm start the engine and allow it to tick over whilst it pumps the old fluid into the bucket. As soon as bubbles start the assistant should start pouring the new fluid in to replace the old. Switch off the engine when bubbles again start appearing at the open hose.

Reconnect hose, pour in about half of what should go into the box, start the engine again, and top up accordingly checking with the dipstick.

Dexron III is semi-synthetic, the more expensive III's like Mercon and Millers will be fully synthetic. Personnally I would use the cheaper II and flush it around about every 20k miles. The Honda box in the 416 is pretty long lasting anyhow, but every little bit of TLC helps!

Tim..

Reply to
Tim (Remove NOSPAM.

There's some debate about this, but BMW apparently now recommend a change at 100,000 miles on their 'sealed for life' autos. And they use fluid rather more pricey than Dexron.

If the fluid has gone black through internal slipping, there's no point in changing it. The box is toast.

Reply to
Dave Plowman

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