as title says I need to know wat oil or what weight oil to use in my su as I want to get it running tomorrow! I'm using a cd175 su in a drawthrough turbo setup, any help would be good. Ta nick

Datsun recommended 20W or 10W30 Elephant Oil, but any brand of motor oil will work. This was for Datsun Hitachis but I would guess british SU probably are tuned with similar oil weight.

the idea is to stop flat spotting when the needle goes up.. the XU-1's used auto trans oil in winter and none in Summer,
start off Light,
if you find they are going up too fast, try some heavier oil..

ther is "Propper" SU damper oil on ebay, but you'll find ATF will most likely keep you happy.

yea auto trans fluid or sewing machine oil works good too

thanks for the help will see how it goes tomorrow with atf

ring me in the morning nik

i have a friend using the bluebird 910 SSS, stock twin SU. he's been using the sewing oil for a while. so i recommend him the ATF oil. the feedback is very positive, better acceleration, need to top up the oil less regularly.

the oil works like an accelerator pump. It slows the piston in the carb from rising, so for a split second, there's a stronger signal on the jet, until that piston has risen up, so it enrichens the mixture. So essentially you only need it thick enough to get rid of any flat spots. Anything more than that, and, much like a 'too big' acc pump cam/squirter combo on a holley - it'll only use more fuel than it needs to to get the job done.

Beyond the flat spot issue/acc pump equivalent as mentioned, if it shows to accelerate noticeably better with thicker and thicker oil, it's actually a sign that you need a richer needle.

I always used the same oil that I used in the engine, principally because I was too lazy, & too 'tight' to get ATF.
It was also always available in the event that the carbs needed a top up.

There was no noticeable problem with performance & in fact, during winter which often meant sub zero temps, the engine performed flawlessly, so the thicker oil, when cold, essentially substituted for a choke.

My driving was mostly highway so there was little need for slaming the throttle open, however, once the engine was properly warmed, the oil thinned & quick acceleration was always a feature of my humble big bore GX.

I ran it like this for so long that a baby born on the day that the GX went into the car, would have been eligible for a licence by the time that the car was decommisioned.
Never had a problem.

here in malaysia we got no winter, and the SU (bluebirds, not GX) carbs is really dirt cheap. i dunno why bluebird users here hates the stock carb.


do the oil in carbs get heated during a long drive in summer? it is really hot in here. and do i need to change the oil at specified interval?