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Thread: Anyone have a link to oil viscosity graph

  1. #1
    Join Date
    Dec 2003
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    Default Anyone have a link to oil viscosity graph

    Anyone have a good link to an oil viscosity graph so I can compare

    SAE 30 oil to

    10W-30, 10W-40, and most importantly to 15W-40

    5W-40 would also be nice too.

    I need to put some oil in a Kubota diesel engine and its first recommendation is SAE 30 with or 10W-30 or 10W-40 as options for above 25C ambient.
    97 5spd K2500 Ext Cab short Bed ~160K miles.
    TM, 3" downpipe & 4" exhaust, remote FSD, remote oilfilter, Gauges: EGT, Boost, Fuel Pressure, B&W Gooseneck Turnover ball, Prodigy Brake Controller. Hi-Temp Hydraulic Oil Cooler Lines.

  2. #2
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    Default

    '94 GMC 6.5TD K1500 4L80E 2-Door Yukon SLE 221K
    '93 Chevrolet 6.5TD K2500HD NV4500 Std. Cab Longbed 187K
    '85 Toyota 22R RN60 4x4 Std. Cab Shortbed 178K (Currently retired for rebuild)
    Diesel Page Member #2423

  3. #3
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    Dec 2003
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    Default

    Thanks,

    I was kind of hoping for one like this but maybe more readable or a little clearer.

    http://www.widman.biz/Seleccion/Visc...aph/graph.html

    I looked at bob is the oil guy site then put in 100 and 11 for viscosity in the above table/graph for 40 and 100 C temps and it looks like for temps above 25C / 77F - SAE 30 and 15W-40 are pretty close equivalent in viscosity index. Then differ more and more the colder you get.

    Which kind of makes me wonder why they recommend SAE 30 OR 10W-30 and 10W-40 but no mention of 15W-40 as its the most common diesel oil in the US.
    97 5spd K2500 Ext Cab short Bed ~160K miles.
    TM, 3" downpipe & 4" exhaust, remote FSD, remote oilfilter, Gauges: EGT, Boost, Fuel Pressure, B&W Gooseneck Turnover ball, Prodigy Brake Controller. Hi-Temp Hydraulic Oil Cooler Lines.

  4. #4
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    SC
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    A Kubota rep said if it wasn't listed in manual then DON'T use it or it will void the warranty.

    I went again to compare SAE 20, SAE 30, and 15W-40 and for temps above 25C-77F 15W-40 looks equivalent to SAE 30 but see where SAE 30 is more viscous at lower temps and appreciably changes. And at near freezing the viscosity difference appears significant from SAE 20 vs 15W-40. More than I would expect. As I was thinking the 15W was kinda close to SAE 20 at cold temp but 15W is still appreciably more viscous.

    I kinda wonder how accurate the graphs are due to a 2 point curve fit (doesn't differentiate that I can tell for straight vs multi-viscosity) and its an unkown internet source of info and I am estimating the 2 pts from bob is the oil guy site. So if someone has a good Viscosity graph with the above oils I am still interested.
    97 5spd K2500 Ext Cab short Bed ~160K miles.
    TM, 3" downpipe & 4" exhaust, remote FSD, remote oilfilter, Gauges: EGT, Boost, Fuel Pressure, B&W Gooseneck Turnover ball, Prodigy Brake Controller. Hi-Temp Hydraulic Oil Cooler Lines.

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