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oil grade


navyguy
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Looking in the spitfire 1500 handbook it says that for dependant on the ambient temperature the grade of oil can range from 10W40 all the way up the grade scale to 20W50. Can anyone tell us why we tend to use the more expensive 20W50 rather than the standard 15W40???

 

Cheers

 

Navyguy

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Because 30 years ago, it was standard 20W50 and more expensive 15W40. Technology moves on and so does demand, hardly anything needs a 20W50 now.

 

Modern 15W40 are too thin really for the Triumph engines, especially ones that are not in 100% condition, it tends to give low oil pressure and find gaps to leak out of that a 20W50 doesn't.

 

And try to avoid the cheapo 20W50's, some of them really are a bit rubbish.

 

Look out for Valvoline on special at Euro Car Parts, or splash the cash and go for Millers 20W50 (or even 20W60) Classic Sport.

 

Neither will disappoint.

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The grade of oil specified depends on the ambient conditions.  According to the owner handbook, 20W/50 is recommended for operation from 0 to 30 deg C., 15W/40 from -10 to 30 deg.C.  If you care to drive around with the top down at -30 to -10 deg.C then you should use 5W/40.

 

I always use a 20W/50 from a reputable supplier and maintain 60 psi cruising on a warm day.  If it is -10 deg.C then I probably will not be driving so no need for the 15W/40.

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