G15 engine and transmission oil?

[GinELla]

What brand, type and viscosity oil do you recommend for a G15 998 cc Imp Sport OHC stage 7 engine (R17 camshaft, one double 40 millimeter Dellorto)? What brand and type of transmission oil is the best?

Edited by GinELla on Friday 29th May 00:17

[GinELla]

Found some info about oil in the old (20 years+) papers that I got with the G15. 20W-50 is recommended for the engine, although there is no note of the air temperature range. As there is no heater fitted as standard in the G15, I guess this - as usual - is recommended for air temperatures above 20 degrees C. On the shelf I had some 20W-50 Quaker State mineral oil which is exellent for old, American, cast iron, push rod V8s with hydraulic valve lifters. We'll se if it's OK for the Imp engine or if it's too sticky for the modern, high revving OHC Imp stage 7.

I found an oil filter not listed in the documentaton, Knecht OX13 by Mahle. Only neagive thing is that only square seals in two sizes were in the box. I cleaned the old seal and groove and reused the old O-ring seal.

When I checked the transmission oil I found that the oil looked brand new and it was just the right level, so I left it as it was.

Edited by GinELla on Sunday 21st June 17:47

Edited by GinELla on Monday 22 June 22:59

[blitzracing]

Oil technology has move on a long way and oils now cover a much wider temparature range and are generally "thinner" without causing metal to metal contact, so you dont need to worry about finding a 20-50. A good quality synthetic 10-40 should be fine, although we used to all way used Mobil one on the race engines. Its very low viscosity these days, and I dont know if the oil pressure will hold up on the Imp engines although thinner oils do absorb less horse power.

[ccharlie6]

for the engine i use a a good 20W/50 such as castrol classic, this is in a 998 hartwell running twin 40's
transaxle i run castrol syntrax 75w-90 which is low friction and aids gear changes however if your seals arent up to scratch it will find its way out! ive heard very good things about redline oils for gearbox's like shockproof lightweight so will investigate those soon.

[GinELla]

Thank you, Ccharlie6 and Blitzracing! I'll run the Quaker State until next oil change, then change to synthetic.

When I start to drive the G15, after passing the mandatory bi-annual EU control (PKK - periodisk kjoretoy kontroll - in Norway, I think it's called MOT in the UK), I'll see if the gear shift seems OK or if I should change to Castrol Syntrax 75w-90. It's more than 25 years since I've driven a manual transmission vehicle on a regular basis.

[timg4d]

Whatever you do, do not put Redline transmission oil in an Imp transaxle. There is nothing wrong with the oil, but it is simply not suitable (too thin) for a gearbox designed in the early 1960s. If you use it, the box will seize after about 200 miles. I speak from hard won experience! You have been warned. I would suggest EP80 or whatever the gearbox builder recommends. For the engine, I used Amsoil Racing 20/50 for a 115 bhp 998. Ian Carter reckoned it was good stuff. The key point is the viscosity - Imp engines throw oil out if you use modern thin oils.

[ccharlie6]

cheers for that info on the box seizing... ill stick to the syntrax for now. the redline stuff has a very good rep but as you say is designed for modern transaxles such as a porsche G50 not an imp tranny.

would still love to run my engine on castrol R40 (for the smell more than anything!!) just don't think i could stomach the costs

[mikeg15]

Standard Imp transaxles are very sensitive to having the correct oil. The difficulty is the brass (bronze?) bushed gears which will sieze given half a chance. It happened to me at one time when I was towing my car using an 'A' frame. Early Imp racers machined oiling grooves in the bushes as a part solution to the problem. Years ago I was told that there was a gearbox specialist in the UK who did needle roller conversions which solved the problem, don't know who though.

[Comadis]

the chrysler-uk workshop manual recommends the following lubricants for the transaxle:

shell spirax 80 E.P.
below 15 degrees celsius: spirax 75 E.P.