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correct ATF for the BW35

GordonD
Posts: 20
Joined: Thu Apr 30, 2020 6:52 pm
Location: Ramsey, Isle of Man

correct ATF for the BW35

Post by GordonD »

I have come across conflicting reports over which is the correct ATF for the BW 35 box. I confess to knowing little about auto boxes and My V8 250 came in March with dexron2 based ATF which although the box works in P, R, N and D1, it does not in D2 or L and it is not as smooth as I would have hoped. Could this be due to the ATF choice? I have seen in another website for Rover cars that the BW35 must only use ATF-G and not a Dexron based product.

May I ask the experts out there (who have helped me enormously so far with this project) for their words of wisdom?

Gordon

Bud
Posts: 318
Joined: Fri Feb 12, 2016 9:06 pm
Location: Rochester, NY

Re: correct ATF for the BW35

Post by Bud »

This could contain your answer. Type F

https://en.wikipedia.org/wiki/Borg-Warn ... ansmission

KV8
Posts: 304
Joined: Sun Mar 06, 2016 7:05 pm
Location: Cambridgeshire

Re: correct ATF for the BW35

Post by KV8 »

Hi

As well as my V8 saloon I also have a Trumph Stag which also uses the BW35 Autobox on earlier models and the BW65 on later models. The Stag consensus of opinion is that one should never use Dexron fluids in these boxes. The favoured fluid is comma AQF
https://www.opieoils.co.uk/p-147632-com ... fluid.aspx

I would change the fluid for the above but it may be tens of miles and frequent change of speed before full functionality returns . If it does then £30 well spent and then I would change the fluid again. If it does not then Stag user opinion indicates that the Dexron use has caused permanent damage. Never fully understood but apparently something to do with the clutches. Perhaps some one more conversant with the operation of these gearboxes can explain.

HTH

H

classiclife
Classic Wise Man
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Location: Ridgewood - East Sussex
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Re: correct ATF for the BW35

Post by classiclife »

Hello Gordon,

When I had the BW35 in my V8-250, I used Penrite Classic ATF which proved to be excellent and gave a very smooth gear change.

The Daimler autobox requires a TYPE A fluid.

May I suggest that the failure to engage D2 and L is an adjustment issue and not the oil.

Regards.

Richard.

https://www.classic-oils.net/Penrite-Classic-ATF
1968 Daimler V8-250 Saloon
DLOC East Sussex Branch Secretary
DLOC 2.5L V8 & V8-250 Registrar - https://www.dloc.org.uk/v8-250
DLOC 2024 International Rally - https://www.dloc.org.uk/rally-2024

bobtills
Posts: 186
Joined: Wed Sep 25, 2019 6:05 pm
Location: North Wales

Re: correct ATF for the BW35

Post by bobtills »

As you've said, you can find posts on forums which tell you every possible combination being right, or wrong, as is the experience of individual owners.

The same argument exists for brake fluid - DOT 4 or 5 - and engine oil.

I always use the 'old fashioned stuff' for everything where possible as this was what the designers expected you would use, and built your car accordingly. I know it's possible for fluids to get 'better' as time goes on but I'm not convinced. The stuff they put in a more modern type of fluid can attack seals & clutch material in a 'box designed for an older type of fluid, like synthetic oil can attack the seals in your engine and modern petrol can attack seals & gaskets in your fuel system.

On forums I see that if your 'box has been fully reconditioned you can, apparently, use Dextron fluid, and that might be true - or the owners might just be lucky, or only done a few thousand miles since - but as you can't get rid of all the old fluid just by draining it you will end up with a mix, which is definitely not what you want. But I would stick to the 'Ford' stuff - I has a BW35 in the 1970s which I took to 140,000 miles with no trouble at all, using the old type fluid. So there's nothing wrong with it.

KV8
Posts: 304
Joined: Sun Mar 06, 2016 7:05 pm
Location: Cambridgeshire

Re: correct ATF for the BW35

Post by KV8 »

classiclife wrote: Thu Jul 16, 2020 8:45 pm Hello Gordon,

When I had the BW35 in my V8-250, I used Penrite Classic ATF which proved to be excellent and gave a very smooth gear change.

The Daimler autobox requires a TYPE A fluid.

May I suggest that the failure to engage D2 and L is an adjustment issue and not the oil.

Regards.

Richard.

https://www.classic-oils.net/Penrite-Classic-ATF
I regret I must disagree with your recommended fluid - it is a Dexron base type.

There are in excess of 3000 Stag Owners using this gearbox and the recommendation is never use a Dexron base fluid in this gearbox. It was also used extensively in Rover P6's and I quote from their owners club website:-

"When topping up the gearbox fluid, you MUST use the correct fluid – ATF-G or Ford spec M2C-33G. Other fluids sold for modern automatics are normally Dextron based and destroy the integrity of the clutch and band friction linings. The gearbox will almost certainly fail after only a couple of thousand miles with Dextron instead of the correct fluid."

http://p6club.com/content/borg-warner-automatic-gearbox

I have not personally heard this but it is possible Bobtills comment that modern rebuilds may be OK with Dexron is correct.

H

classiclife
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Re: correct ATF for the BW35

Post by classiclife »

Hello,

Sackcloth and Ashes for me.

As Bud pointed out initially the BW35 if a "F" type and not an "A" as I had indicated.

Apologies for the error, Gordon.

Indeed my autobox had been rebuilt, hence the oil I pitched - thanks Bob & H.

Regards.

Richard.
1968 Daimler V8-250 Saloon
DLOC East Sussex Branch Secretary
DLOC 2.5L V8 & V8-250 Registrar - https://www.dloc.org.uk/v8-250
DLOC 2024 International Rally - https://www.dloc.org.uk/rally-2024

daimlerfan
Posts: 63
Joined: Sat Feb 13, 2016 11:43 pm
Location: London

Re: correct ATF for the BW35

Post by daimlerfan »

Hi,
When i had my Gearbox refurbished by Whitehouse It was filled with Dexron type 2. I queried this and I was told with the replacement modern parts it was Ok to use a Dexron Base Oil but not with the original old parts.
So i have continued to use Dexron II with no adverse effects.
1969 Daimler V8 250

GordonD
Posts: 20
Joined: Thu Apr 30, 2020 6:52 pm
Location: Ramsey, Isle of Man

Re: correct ATF for the BW35

Post by GordonD »

Thank you everybody for a lively debate! My engine and drive train were rebuilt by the previous owner. I have numerous photographs and the work looks to be of high quality but does not, unfortunately, give the identity of the engineer who did the work. It would have been ideal to have been able to speak with him.

I tend to agree that the non-functioning D1 and L are an adjustment issue but have yet to find a way of making that adjustment as on the gearbox, the selector lever clicks positively into each of its 6 positions. It will be back on the ramp next week and I will have another look around

If the gearbox has been rebuilt, perhaps Dexron2 based ATF is fine, but older ATF would not harm it. On the other hand if it has not been upgraded, then older ATF is required and Dexron2 could cause deterioration. Logic suggests that older ATF is the safer way to go as suggested by the Stag and Rover owners' experience, involving several changes to flush the box.

Excellent advice, all. Thanks again.

Gordon

Ian Hastings
Posts: 163
Joined: Tue Mar 15, 2016 3:00 pm

Re: correct ATF for the BW35

Post by Ian Hastings »

You are going to have a large amount of old ATF to dispose of so why not mix it 50/50 with acetone as that creates a very efficient easing oil, much better than the commercial stuff like WD40 etc. :) :P

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