Differential Oils

[John042]

Hi, some confusion over correct grade of Diff' oil. My 1996 Chim' TVR Owners Handbook states "Mobilube HD90/SAE 85W90. The bib** states "Mobil SHC 80W - 140ID. I'm conviced that according to the servicing records 80w90 would have been used. So have I got the correct oil in the Diff' or should I be using the higher viscosity 80W - 140ID? There is a slight whine on the over-run when hot (40 miles+) Any advice appreciated, thanks. John042

[Pupp]

Depends which Diff you have. Earlier cars generally had GKN (heavy finning is easy way to identify) that requires the 85w90; later ones had BTR units that use the 80w140. Important the right spec fluid is used

[carsy]

I have a gkn diff and have just put some castrol lsd 75 140 in after several people on here have recommended it for the gkn.

[Pupp]

The 75w140 will be fine for the GKN but don't use 80w90 in the BTRs

[Simon says]

carsy said:

I have a gkn diff and have just put some castrol lsd 75 140 in after several people on here have recommended it for the gkn.

It works great in the GKN and is in fact over spec which is nice don't worry

[John042]

Thanks all for the replies. My Diff is 'Finned' so I guess it's a GKN. My friendly garage, who give me excellent service are of the opinion that the correct oil, (As stated in the Handbook HD 90/SAE 85W90) is the correct oil to use. I quote " John, you are sitting in a plastic tub inches away from rotating assembles with straight-cut gears transferring drive through 90 degrees, keep your left foot down, roof off and enjoy" Un-quote. So I think I'll take his advice. Cheers John042.

[Simon says]

Not straight cut gears and its hardly going to fail because you have fitted a superior oil have you heard the one about using only 20/50 motor oil in the RV8 because it is such an old design bloke down pub said......................... so long as your happy

Edited by Simon says on Wednesday 18th May 11:51

[M@H]

John042 said:

Hi, some confusion over correct grade of Diff' oil. My 1996 Chim' TVR Owners Handbook states "Mobilube HD90/SAE 85W90.

Hi John, I reckon you may have got the wrong book with your car. On page 44 of the Chimaera Owners handbook I have it states "Differential - Mobil SHC 80W 140ID - 1.6 litres" perhaps you have one from the cars with the other Diff?

Cheers,
Matt

Edited by M@H on Wednesday 18th May 11:40

[darkcat]

Mines a late '96 and is fitted with the BTR diff -
both the handbook AND lubrication plate say mobil 85w90, however there is a supliment in the hand book that states it MUST be used with 80w140 (i think).
Ive just bought 2 litres of this:

http://www.millersoils-online.co.uk/M3_cgi/millers...

should do the job nicely

[John042]

Confusion is alive and well! The plate on my car states HD90 as does the handbook. There's no supplement in the book. My garage have taken advice from two main TVR Agents who maintain the information contained in the book and on the plate is correct, unless of course a latter BTR Diff has been fitted. No evidence of that happening. So I guess I'll take their advice? Interesting though about the supplement in the handbook? Thanks again for the interest and advice. John042

[M@H]

..very odd considering Page 44 in the Manual I have is definately not a suppliment either !

[John042]

Hi, M@H my handbook page 44 is 'Saftety Precautions etc' If yours is a late 1996 perhaps you have a BTR diff fitted? John042

[darkcat]

keep a close eye on it (!), i had the incorrect oil in, and it nearly seized (caracterised by loud clunks when trying to turn on full lock)

[M@H]

http://sites.google.com/site/lordgrover/Home/usefu...

[John042]

Hi M@H. My book is dated August 1995, your link shows January 1997. Is this the period when TVR changed Diff types from GKN to BTR? As the January 1997 book shows other differences, ie the later dashboard layout. I had a quick 'grovel/limbo under my car at lunchtime to confirm that it was a finned casing on the Diff (GKN) Cheers John042.

[M@H]

1996 is a funny year really as the "facelift" model didn't just come in all at once at one date - a 1995 car should definately be pre-facelift and a 1997 car would be facelift, bits in the middle can fall into either camp but you are right IIRC I recall the diff changed in 1995 along with the gearbox change. (someone will correct me shortly !)

Its all good anyway

Matt

(With a facelift 1996 car)

[John042]

Hi M@H, I think you've 'hit the nail on the head' My car was first registered 01/06/96. Probably the period you mention when the last of the pre-face lift ones were being sold. Mines fitted with the T5 gearbox, dash layout with heater fan switch top left position and GKN Diff. Servicing records from new suggest that HD90 has been used throughout its life. It was only a slight whine on the over-run that raised the possibility of the wrong oil. Cheers and thanks again for your interest. John042