I'm gunna freshen up the oil (or top up, there might not be any in there, lol) in my twin 1.25" SU's, and I was wondering what oil to use? I have heard engine oil isn't good at all for them.

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Most common are 20W/50 motor oil, or ATF (Dexron 2 or 3)

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Try using motorbike fork oil. Its about 10W and still lubricates well

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Master of the obvious - Prophet of the past

I got some general house oil stuff from AutoPro, it's what they recomended me. The car is going in to get the twins tuned soon at "rally carb" here in Geelong, so I guess they will put the right stuff in then.

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In the UK they were using very light oil like sewing machine oil (and I think thats what Haynes recomend) but in Aust. where its much warmer, normal engine oil (which is the 20/50 the Dr is refering to) should be fine. Just make sure to get the oil into the chamber (cant remember the name for the life of me) rather than around it. And you only need a few drops.

i've been told that a light oil works best.. and one person ever recommended wd-40 now thats what I call light oil!

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...its leaking oil... and thats a good sign!
It lets me know that I havent run out yet. -Tzi 4-9-04

lol, while searching bunnings for something (we had no luck at supercheap, so went to bunnings which is in the same complex), my father said "you could always use WD-40."

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20 yrs on the job and have only ever used 'singer machine oil' its cheap, 10w, and readily available, comes in those handy oil bottles. I would'nt recomend motor oil as its to heavy and affects the dash-pot piston raise and drop speed which will cause your motor to run lean on accel and over-run on decel.

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go stop...go..stop..go. stop..go...stop...Damn malls are crowded

Sorry Animal, but "which will cause your motor to run lean on accel " ......

Isnt the point of the Dashpot oil to DAMPEN the movement, so that when there is a drop in vacuum (as in accelleration) the dashpot wants to raise very quickly, but the heavy oil slows it down, raising the airspeed over the bridge of the carb, increasing the "accellerator pump" effect ..... RICHENING the mixture ?

I know mine is a lot nicer in start stop traffic with a heavier oil (Penzoil 20/50) than a light one (ATF / Marvel Mystery oil)

Just simple physics...........
J

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true true...but with the thicker oil air speed is increased but the needle is slower to retract which will decrease fuel supply...have tested with air/fuel meter on diag mach and although common sense says otherwise, accel is lean with thick oil....

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go stop...go..stop..go. stop..go...stop...Damn malls are crowded

I run 3in1 oil and a red spring in my single HS2 carb (with quick-lift piston) and I think it's great - very responsive. You do notice a very slight flatspot, because of the lack of 'accelerator pump' function caused by a thicker oil - but I tune a little on the rich side so it isn't a problem. I tried 20w50 once, round the block, and the car was S.L.O.W! It made a serious difference. I noticed that even with ATF it was a bit slower - but I guess playing round with needles I could fix that.

We've always used singer sewing machine oil here and never had any problems. I just used it as thats what my father always used when it was his car... seems to work tho