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Dashpot Oil

Posted by Phantom 
R K
Cobourg Ontario, Canada   can
1966 MG MGB

I tried buying SU dashpot oil at a local MG parts supplier and was told just to buy straight 20W as he didn't stock the actual dashpot oil anymore.

I tried to buy 20W locally but found out that no one seems to stock it anymore. Any other suggestions?

Also when adding the oil, to what level are the dashpots actually filled?

RK
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twigworker Avatar
Jack Austin
Blowing Rock, NC, USA   usa

Many opinions to come, but IMHO use whatever you are using in your crankcase. If you use your B in severely cold weather perhaps MMO would be better, but you prbably already know that.

Jack

Jacks Cars - Services To Interesting British Automobiles Over 40 years of caring and capable services to British cars and their owners. For help or advice please call 828-295-0224, email to jackscars@charter.net or go to www.jackscars.net.
JMoore Avatar
John Moore
Clifton Park, NY, USA   usa

I was using ATF, but recently switched to the heavier 20W50 so it doesn't lean out under hard acceleration.



John Moore

'70 MGB, '68 MGBGT, '99 Land Rover Discovery II, '61 Austin Healey Bugeye Sprite
ourmg Avatar
George Heissenberger
Victor, New York, USA   usa
1973 MG MGB "OUR MG- The Old Girl"
2006 Mini Cooper "Greta's Mini"

I was told years ago by the then BL dealer to just use what is in the crankcase and I have used 10W30 for 20+ years in two different MGB's.
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mac townsend Avatar
Fairfield, CA, USA   usa

I switched from ATF to rear end 70W-140 (a few drops of Redline left in a bottle was plenty for the purpose) weight stuff yesterday. That's also John Twist's current recommendation.

At the same time I put in a set of AAA needles, replacing the AAEs in my AUD405 HS4s. Car ran super on a 230 mile jaunt. And I didn't even retune the jugs, though I should have.

I think I'm gonna put the AAEs back to see what diff the 70 had by itself.

I was getting slight stammering at cruise, indications of a bit of leaness. The combo solved that. Now I'm curious to see if the oil itself might have fixed it.
Terry Ingoldsby
Calgary, Alberta, Canada   can
1971 MG MGB

I hadn't thought of trying rear-end oil. Although the numbers make it look awfully thick, they apparently use a different rating scheme than engine oil. So 70w-140 isn't three times thicker than 20w-50 despite the numbers.

Now, it is a good question whether to use multi-grade oil or straight weight. Multi-grade oils maintain their viscosity regardless of temperature. So, damping effect will be the same whether the weather is cold or warm. On the other hand, straight weight oils are thicker at colder temperatures. That might give some added dampening when it is most needed.

I've always run crankcase oil (currently 5w-50) and have no complaints.



Terry Ingoldsby
terry.ingoldsby@DCExperts.com
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Peter Thomas
Victoria, Australia   aus

RK,
This one has been debated more times than I can recall.
If you want to trawl the archives there are a lot of pro's and con's being chewed over.

The general trend is to use whatever is in the crank (normally 20W-50 of your favourite brand) since there is bound to be some of the same in the garage somewhere.

From personal experience I have used ATF , Shell 20W-50 , machine oil ( a lightweight general purpose oil about 15W or so) and a few others and found no discernible difference for a road car.

Fill the carb dashpots to about the level of the outside bell top where it flares into the neck.

Pete.
Basil Adams Avatar
About 12 miles from Sears Point, CA, USA   usa

A zillion opinions tells me that there aren't any bad answers. I've tried many of them and they all seem to work. Marvel Mystery works (and it's my forst choice). Hydraulic tool oil works. ATF works. Motor oil works. Castor oil works. In the race car, I run without oil but I take the tops off the carbs and clean them 2-3 times a weekend - ending with a light spray of WD-40. Enjoy!



Basil C. Adams
1956 MGA Coupe (Show Car)
1957 MGA Roadster (Driver)
1958 MGA Coupe (Racecar)
1959 MGA Coupe (unrestored)
1960 MGA Coupe (unrestored)
1960 MGA Roadster (Driver)
MKIII Elva Courier (E1056)
1967 427 Cobra
1972 Alfa Romeo Montreal
A coupla late MGBs
1960 Austin Healy BN7
More Cars than Brains
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R K
Cobourg Ontario, Canada   can
1966 MG MGB

Thanks for all the answers...it almost sounds like you can use whatever your preference is and be fairly safe.

RK
GILMGA Avatar
Gil Dupre
Chattanooga, TN, USA   usa
1962 MG MGA
1974 MG MGB GT

Jon Twist recommends 80/90 gear oil
bout the same viscosity as 20 50 motor oil



Gil
chris Avatar
Chris Roop
Pendleton, OR, USA   usa

Pretty much. The purpose of the oil is to regulate the lifting speed of the piston in the carb. So, weather conditions local to you will determine which choice is best.

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mgbjockey Avatar
Frank Patton
Eastern Shore area of Maryland, USA   usa
1969 MG MGB "Sapphire"
2010 Mini Cooper S "Hot Pepper"

The rebuild video says the closest thing to dashpot oil and readily available is 20W motorcycle fork oil.




*************

Frank
MGBJockey

Shinsen774 Avatar
Jim '64MGB
Virginia, USA   usa
1964 MG MGB
2003 Mazda MX-5 NB "Shinsen Version #774"

mgbjockey Wrote:
Quote: The rebuild video says the closest thing to dashpot oil and readily available is 20W motorcycle fork oil.

Which you can get at your local Honda motorcycle dealer. You also use this in your dampers/lever shocks.





Edited 1 time(s). Last edit at 05/07/2007 03:12PM by Shinsen774.
max71 Avatar
Gary Alpern
Portland, OR, USA   usa
1971 MG MGB "Max"

I was about to chime in with ATF. I tried the moss stuff and it slowed acceleration. I did 20/50 - same. I like ATF. I'm interested in trying fork oil. Interesting.
ourmg Avatar
George Heissenberger
Victor, New York, USA   usa
1973 MG MGB "OUR MG- The Old Girl"
2006 Mini Cooper "Greta's Mini"

So the opinions range from just about any kind of oil you can name to none at all except a little WD-40. Amazing.
R K
Cobourg Ontario, Canada   can
1966 MG MGB

Interestingly enough the local Canadian Tire did have straight 20W in the form of motorcycle "Fork Oil"
It isn't cheap though...it was over $10.00 with the tax for about 1/2 a quart.

Thanks for all the answers!

RK
Jim K Avatar
James A. Krasnansky
Liberty, KY, USA   usa
1970 MG MGB GT "Chloe"
1971 MG MGB GT "Roscoe"
1972 MG MGB "Camilla"

I'm with Basil on the Marvel Mystery Oil.



Jim K is a grease-stained wretch
fleshy1 Avatar
Eric Triplett
Monrovia, CA, USA   usa
1978 MG MGB
2005 Audi S4 Avant "The Sled"

mac townsend Wrote:
Quote: I think I'm gonna put the AAEs back to see what diff the 70 had by itself.
I was getting slight stammering at cruise, indications of a bit of leaness. The combo solved that. Now I'm curious to see if the oil itself might have fixed it.

I think you'll find that the needle fixed your problem. The AAE is a lot leaner than AAA starting at the 3rd station. Once at cruise the damper oil will have little effect on things since the piston is in a relatively stationary position.




Eric Triplett
"Electronic ignition, the greatest thing that ever happened to carburetors."

1968 High Compression Engine, Dual SU HIF-4 Conversion, Peco Header and Exhaust, Pertronix LU-147, MSD Blaster 2 Coil. Advanced Distributors Re-Cruve 45DM

Jim Smith
CASSIDY, BC, Canada   can

The owner's hand book specifies the same oil as in the engine for the gearbox, distributor and carbs.



Jim...Nanaimo, BC
1971 MGB collector
1975 MGB driver
1975 MGB in pieces waiting for V6
2005 Mini Cooper

A wise man overhauls his brakes before his engine.
JackMG Avatar
Jack Lindler
Greenville,SC, USA   usa

Thinner oils allow the damper to respond more quickly to throttle (vacuum) changes. hap says in his racers, they don't even use oil - run them dry.
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