bcrain Posted September 13, 2018 Share Posted September 13, 2018 I have looked through the many posts on the proper gear oil to use and whine problems. I have not seen comments on the best oil for cars that are in the US. Different products are available here. My 1988 Di Dion seven says Spirax 95/140 on the chassis plate. That is a Shell product unavailable to my knowledge in the US.Hey all you yanks out there, what do you use? Would Valvo line 85W140 be OK? Link to comment Share on other sites More sharing options...
Wrightpayne Posted September 13, 2018 Share Posted September 13, 2018 I use ford EP90 here in the UK. It is used in the Ranger gear boxes and diffs. I’m sure there will be an equivalent for pick ups etc in the USA.Ian Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted September 13, 2018 Member Share Posted September 13, 2018 My 1988 Di Dion seven...Which final drive: Sierra?And not limited slip?Jonathan Link to comment Share on other sites More sharing options...
Area Representative Geoff Brown Posted September 13, 2018 Area Representative Share Posted September 13, 2018 If the final drive is Sierra then: standard diff - any good 80w/90. If LSD - Castrol 373 comes highly recommended.70w/140 or 80w/140 is good for shock absorption & lowering noise but as far as I know is not a recommended lubricant for Sierra diffs. Most of these spec products are for LSDs.Castrol Syntrax LSD 70w/140 is recommended by Castrol for the BMW LSD. I put it in my BMW LSD & the change was miraculous. Link to comment Share on other sites More sharing options...
bcrain Posted September 13, 2018 Author Share Posted September 13, 2018 I looked up the original invoice for the car. It says: "Rear Axle Assembly (CXD)" and charges 1050.00 pounds in October, 1988. Anyone know what kind of diff it has? Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted September 13, 2018 Member Share Posted September 13, 2018 You can test if it's open or a traditional LSD by jacking up the rear wheels, turning one and watching the other.Or by looking through the hole with a driveshaft out.But if you don't know that it's anything else the year and specification strongly suggest that it's an open Sierra final drive.If you would like the appropriate Assembly Guide please send me a Private Mail with your email address.Jonathan Link to comment Share on other sites More sharing options...
bcrain Posted September 13, 2018 Author Share Posted September 13, 2018 Based on the year I should have a Sierra and it tested as NOT LSD. One of the Caterham dealers in the US who also does a lot of racing returned my call and recommended Mobil 1 75w-140 for maximum gear protection or the same in 75w-90 for slightly more horsepower due to reduced parasitic drag. I'm going with 75w-140 for now. I'll plan or reporting back after my excursion to the northern NM mountains in a couple of weeks. Link to comment Share on other sites More sharing options...
SM25T Posted September 13, 2018 Share Posted September 13, 2018 I am going to try Castrol B373 next ... after a recommendation here. Link to comment Share on other sites More sharing options...
7 wonders of the world Posted September 14, 2018 Share Posted September 14, 2018 Castrol B373 is spot on for plate LSD'sThere's a seller on fleaby selling it for £9 / Ltr post free Link to comment Share on other sites More sharing options...
Molecular--Bob Posted September 14, 2018 Share Posted September 14, 2018 Is it ok to top up original ford lsd oil (diff is ZF plate type) with B373 or should i empty and re-fill? Link to comment Share on other sites More sharing options...
Area Representative Geoff Brown Posted September 16, 2018 Area Representative Share Posted September 16, 2018 Empty & refill. Oils can be incompatible which will reduce the effectiveness of the new oil leading to problems in the Diff. My experience has found that with LSD oil it is also best to drain & refill regularly....about every two to four years depending on mileage/thrashing as the oil goes really black & appears to change it's viscosity. Link to comment Share on other sites More sharing options...
Speedtrip Posted September 18, 2018 Share Posted September 18, 2018 Geoff,You said the change in diff performance was miraculous with the Castrol. Please tell me more.My BMW LSD is horrendous (whines like a banshee) so I’m keen to find a way of improving it.cheers Andy Link to comment Share on other sites More sharing options...
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