# SU Carb Oil Substitute?



## Rich_Jenkins (Jul 12, 2003)

Anyone have a suggestion for a good commonly available substitute for SU Carb oil?

My trusty Penrite container is pretty much out, and I was checking the dashpots this morning in Magnus and they are zeroed out of oil.

I was going to go down to K-mart or similar and see if I could pick up some light sewing machine oil or similar...?


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## 99flhr (Apr 12, 2005)

wingspan said:


> Anyone have a suggestion for a good commonly available substitute for SU Carb oil?
> 
> My trusty Penrite container is pretty much out, and I was checking the dashpots this morning in Magnus and they are zeroed out of oil.
> 
> I was going to go down to K-mart or similar and see if I could pick up some light sewing machine oil or similar...?


 Hyd jack oil?


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## Clarke (Oct 21, 2002)

Automatic Transmission Fluid(not Ford style).:thumbup:


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## TeamM3 (Dec 24, 2002)

as I recalll, regular motor oil is generally used :dunno:


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## Pinecone (Apr 3, 2002)

IIRC straight 30 weight was used by many.


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## Rich_Jenkins (Jul 12, 2003)

Clarke said:


> Automatic Transmission Fluid(not Ford style).:thumbup:


Cool. Any old kind from K-mart or similar?


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## Scott ZHP (Jul 17, 2003)

Wingspan - I use plain old motor oil in my MGBs dashpots.

Some folks also swear by ATF or Marvel Mystery Oil.

*SU Dashpot oil -* manufactured for the specific application of SUs in STANDARD applications. That is on engines that are completely standard as the manufacturer produced them. It is a little on the thin side, but the whole engine tuning data for each engine is based on using this oil. Used as such it works very well, especially where economy is the main goal and the car is driven very sympathetically.

*ATF -* 'automatic transmission fluid'. A very good substitute where the genuine SU dashpot oil isn't available for use in STANDARD spec engines.

*20W fully synthetic engine oil -* not to be confused with 20W50 engine oil of any sort. Just a 'straight weight' oil. I use this on practically anything where any modifications at all change the spec away from original. This includes any induction/exhaust changes no matter how small. Largely because the engine is likely to see more 'aggravated' use. Active use of the throttle pedal requires a more stabilizing effect on the dashpot piston along with slightly more resilience to give the desired pick-up. The main benefit of the synthetic type is its consistency over a very broad operating temperature range.

*10W/40 engine oil -* gives very similar results to the 20W fully synthetic oil as defined above. It is certainly easier and cheaper to get as most modern automotive engines use this oil. Semi-synthetic is best, although fully synthetic is as good but rare in the price/'what you have in the garage' stakes. Standard mineral oil is OK, but gives poorer performance until the engine warms up unlike the synthetic oils as outlined above.


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## Rich_Jenkins (Jul 12, 2003)

Scott ZHP said:


> Wingspan - I use plain old motor oil in my MGBs dashpots.
> 
> Some folks also swear by ATF or Marvel Mystery Oil.
> 
> ...


Excellent :thumbup:

Thanks Scott...you are a star...


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## Rich_Jenkins (Jul 12, 2003)

frog said:


> Singer 3-1 Oil.
> 
> Faster response time than any other oil.
> 
> ...


Thanks frog...ribbit. :thumbup:


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## SharkD (May 4, 2004)

There's a good primer on SU carbs in the September issue of _Classic Motorsports_ (It may be on their website.)


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