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The mkiv Supra Owners Club

Wrong oil viscosity, what will it cause


hodge

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Hi guys

Im going to change the oil in the car. I've still go almost 2 tubs of Valvoline VRS 5w/50 which I was going to chuck in just to use it up. Now I've been reading about oils for single turbo Supras and it's recommended to use 15w50 or 20w50. If the viscosity of the 5w50 is too thin, what would be the symptoms or would you recommend I just don't use it.

Thanks

John

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Is it not the "50" part that's the issue with a single turbo? I don't really think it's the single itself that's the issue, more that due to being a single tubby it might be getting used harder and the oil temps might be right up there thinning the oil and potentially getting past the rings?

 

Might be making that up though lol.

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the 50 part suggests that it is a higher viscosity when at temp than for example a 40 grade oil (which will be thinner). what people suggest on here is to use 50/60 grade oil when tracking the car as the oil temps and stress can be higher for longer periods of time.

 

imi

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the 50 part suggests that it is a higher viscosity when at temp than for example a 40 grade oil (which will be thinner). what people suggest on here is to use 50/60 grade oil when tracking the car as the oil temps and stress can be higher for longer periods of time.

 

imi

 

At least I was in the right ballpark :D

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At least I was in the right ballpark :D

 

not sure whether a single turbo'd supra needs the thicker oil. mine for example runs lower EGTs now that it is single as compared to when it was Twin - this is a comparison for normal street driving. I don't drive like a loony and don't track the car.

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not sure whether a single turbo'd supra needs the thicker oil. mine for example runs lower EGTs now that it is single as compared to when it was Twin - this is a comparison for normal street driving. I don't drive like a loony and don't track the car.

 

My EGTs don't exide 800 degrees but my oil temp is always around 120 degrees.

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What i tend to think about when changing grades of oil is the original specified grade, which with the Supra from what i remember is 10W30,

 

As people have pointed out the first figure is just cold viscosity, and generally has little impact, other than cold start, and as we don't have winter temps of much less than -10c i really wouldn't worry much.

 

Most people change to a 40w, and some recommend going to 50w, what happens when you start to use a higher viscosity oil is that it will still be 50w at 120c which is not always desirable at high RPMs as it requires more force to overcome the drag created, and the result is often higher oil pressure and a slight sapping of power, now i can see going to 40w as being OK but i personally would hesitate at using 50w.

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