SpitFire6 Posted April 19, 2020 Report Share Posted April 19, 2020 Hi, Why did Triumph spec SAE 20 & SAE 20W oil for early Heralds, Spitfires & Vitesses? Only a couple of multigrade oils were mentioned & 20W50 only once. SU Dashpot oil was to be a monograde. Recommended 20 or 20W monograde in an engine sounds new to me. Cheers, Iain. Link to comment Share on other sites More sharing options...
Anglefire Posted April 19, 2020 Report Share Posted April 19, 2020 Perhaps multi grade wasn’t popular back in the day? I know my vw beetle 1200 was on sae30 oil and none detergent too. Changed every 3000miles. Oil filter was a gauze mesh in the sump. Link to comment Share on other sites More sharing options...
Clive Posted April 19, 2020 Report Share Posted April 19, 2020 I suspect multigrade oils were new, and treated with great suspicion. Probably more expensive than multigrades too. Imagine how thin straight 30 oil gets when hot. OK, it will get as thin (probably thinner) than a modern 5-30 used in the majority of modern vehicles. Suggest using that on here and it would get universal disapproval, and yet the factory specified it! Link to comment Share on other sites More sharing options...
Pete Lewis Posted April 19, 2020 Report Share Posted April 19, 2020 a thicker oil would add more fuel to the acceleration flat spot so ...thicker is better ????? go faster oil !!!! we could sell it in the snake oil market Pete Link to comment Share on other sites More sharing options...
SpitFire6 Posted April 19, 2020 Author Report Share Posted April 19, 2020 Hi, The overseas oil recommendations vs temperature do spec more multigrades. It looks like for winter with monograde is SAE 10 & summer SAE 20? Certainly thin seems the norm from back then. Link to comment Share on other sites More sharing options...
Nigel Clark Posted April 19, 2020 Report Share Posted April 19, 2020 I would expect mono-grade oil to work fine in dashpots. It won't get as got in the carbs as the engine oil does, so won't thin very much. You could argue that mono-grade will work better. When cold and thick it will damp the piston more effectively, giving extra acceleration enrichment. As the engine and carbs warm up, thinner dashpot oil will give less enrichment. So kind of self compensating. 20W50 is too thick for dashpots at any temperature. Nigel Link to comment Share on other sites More sharing options...
SpitFire6 Posted April 19, 2020 Author Report Share Posted April 19, 2020 Here is the WSM where I copied the data from: https://1drv.ms/b/s!AtKuj52yZLQIwZ4vM1iWawlWC_4c7Q?e=9Ptz5F Cheers, Iain. Link to comment Share on other sites More sharing options...
Colin Lindsay Posted April 19, 2020 Report Share Posted April 19, 2020 It was just the simplest option back in the day, and probably the least expensive. "King Pin Lower Swivel"... hmmm. They've even recommended oil for your oil can, too. Link to comment Share on other sites More sharing options...
Clive Posted April 19, 2020 Report Share Posted April 19, 2020 7 minutes ago, Nigel Clark said: I would expect mono-grade oil to work fine in dashpots. It won't get as got in the carbs as the engine oil does, so won't thin very much. You could argue that mono-grade will work better. When cold and thick it will damp the piston more effectively, giving extra acceleration enrichment. As the engine and carbs warm up, thinner dashpot oil will give less enrichment. So kind of self compensating. 20W50 is too thick for dashpots at any temperature. Nigel Nigel, a 20/50 should be the same viscosity as a straight 20 oil when cold, it is just that it doesn't thin as much when hot? so my counter argument is it would be better as give more consistent enrichment during acceleration no matter what the temperature! 1 Link to comment Share on other sites More sharing options...
SpitFire6 Posted April 19, 2020 Author Report Share Posted April 19, 2020 Hi, All the data I have seen suggests a Straight 20 is thinner than a 20W50 at any temperature. Not just the 40C & 100C points. If you find 20W50 that is thinner please share as I have only looked a few. Cheers, Iain. Link to comment Share on other sites More sharing options...
Nigel Clark Posted April 19, 2020 Report Share Posted April 19, 2020 15 minutes ago, Colin Lindsay said: It was just the simplest option back in the day, and probably the least expensive. Yep, we could be over-thinking this! Nigel Link to comment Share on other sites More sharing options...
dave.vitesse Posted April 19, 2020 Report Share Posted April 19, 2020 Multi grade came in and we started using it. Full stop. Car nuts were all buying the 20/50 green stuff, including me back in the 1960's. Dave Link to comment Share on other sites More sharing options...
johny Posted April 19, 2020 Report Share Posted April 19, 2020 45 minutes ago, clive said: Nigel, a 20/50 should be the same viscosity as a straight 20 oil when cold, it is just that it doesn't thin as much when hot? so my counter argument is it would be better as give more consistent enrichment during acceleration no matter what the temperature! Yes I think the cold test is a pour test at -15 or 20 degC so by the time you warm those two oils up to carb temperature there could be quite a difference in viscosity... Link to comment Share on other sites More sharing options...
JohnD Posted April 19, 2020 Report Share Posted April 19, 2020 Glad to see this discussion limits itself to OILS. On US boards, people swear that anything from Automatic Transmission Fluid to Marvo's Magical Mystery Oil will make you dog a racehorse while using less petrol than sailing dinghy. My ha'pny? It depends on your driving style. Try different oils, although changing it isn't easy! A syringe with a long needle is best. Link to comment Share on other sites More sharing options...
Chris A Posted April 19, 2020 Report Share Posted April 19, 2020 If we're adding half pennies. . . I put 20/50 in the dash pots and have no complaints about how the car runs. But I drive a 13/60 convertible, nuff said! Link to comment Share on other sites More sharing options...
SpitFire6 Posted April 19, 2020 Author Report Share Posted April 19, 2020 Hi, I can remember using "3-IN-ONE® Motor Oil is a SAE 20 special blend of high-grade oils" in dashpots. Cheers, Iain. 1 Link to comment Share on other sites More sharing options...
poppyman Posted April 19, 2020 Report Share Posted April 19, 2020 8 minutes ago, SpitFire6 said: Hi, I can remember using "3-IN-ONE® Motor Oil is a SAE 20 special blend of high-grade oils" in dashpots. Cheers, Iain. I can remember my dad always using that Iain. even using it on my bike as a kid. Still have a can now somewhere? But i use 20/50 now like most others. Tony. 1 Link to comment Share on other sites More sharing options...
Mad4classics Posted April 19, 2020 Report Share Posted April 19, 2020 I wonder if service manuals just specify engine oil for carbureters for an easy life. Austin / Morris are just the same with Mini in that early manuals specified 20w/50 but later manuals quote 10w/40 both for engine and carbureter. Basically I can't find a manual that says anything different than "engine oil" - whatever is being quoted for that. Personally I use SU Damper oil; works for me. David Link to comment Share on other sites More sharing options...
SpitFire6 Posted April 19, 2020 Author Report Share Posted April 19, 2020 Hi, It appears that SU Damper oil is SAE 20. Part Number: BDR125SINGLE Description: Damper Oil SAE Grade 20 Cheers, Iain. Link to comment Share on other sites More sharing options...
Pete Lewis Posted April 19, 2020 Report Share Posted April 19, 2020 it justshows how lock down is affecting brain waves , for years on these forums its been Aha, no not dashpot oils again and here we have chapter and verse about what do we put in dashpots think i will take up fishing..........nah.....i hate fishing as well Pete Link to comment Share on other sites More sharing options...
Clive Posted April 19, 2020 Report Share Posted April 19, 2020 A lot of the issue is that as Pete pointed out, thinner oils allow the piston to move faster. The great un- learned thought that was a good thing, must make the car go better. However, for good acceleration you want more enrichment, so a thicker oil is better. Within reason! (not a place for gear oils!) Is 3in1 oil really 20weight? seems much thinner than any engine oil I have used. (such as a 5-30) Link to comment Share on other sites More sharing options...
dave.vitesse Posted April 19, 2020 Report Share Posted April 19, 2020 Not sure if we have covered this, well in with my big feet anyway. The function of the dashpot is to stop the piston vibrating and to delay it rise. By delaying its rise it momentarily enriches the mixture so it acts like an accelerator pump. Thin oil will cause the piston to rise quicker than thick oil. As said winter may call for a thinner oil due to the lower temperatures. However, in the winter generally you need a richer mixture anyway so hence only one type used to be specified. I can remember a Minx, the car, I had in the 1960's where the Solex carb had a winter and summer setting for the accelerator pump. The winter setting gave bigger squirt of fuel. On the SU or Stromberg it's automatic. I can remember the economy drivers putting in the thinness oil they could find! Dave Link to comment Share on other sites More sharing options...
Pete Lewis Posted April 19, 2020 Report Share Posted April 19, 2020 zenith and solex had two ideas the pump stroke lever had two holes you could move the clevis to change the stroke and there was a simpler version with a rotating stop you twiddled to give a long or short stoke nearest we have is on strom cds /cdse there is a winter stop for more choke via a push and turn lever stop. pete Link to comment Share on other sites More sharing options...
SpitFire6 Posted April 19, 2020 Author Report Share Posted April 19, 2020 Hi, found this: https://www.morrislubricantsonline.co.uk/golden-film-sae-20-classic-motor-oil.html About 80 pence for 100mL. Could stick it on eBay as SU oil. The Oil is also API SD so suitable for early cars. Cheers, Iain. 1 Link to comment Share on other sites More sharing options...
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