# how much diff between 15w 40 and 10w 40



## Mr Roo (Aug 8, 2006)

None vw related. Older turbo volvo that is starting to use oil. currently use 10w 30 sythetic since owned. I was told to go to 15w 40 but see 10w 40 as well. I thought 15w 40 was diesel oil, but correct me here. Explain the diff to me.


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## saaber2 (Jul 15, 2008)

*Re: how much diff between 15w 40 and 10w 40 (Mr Roo)*

I would run autorx according to the instructions and then run a 30 weight (such as 10W30) to see if oil consumption stops. If it doesn't stop then you can go to a thicker oil. On my volvo turbo autorx reduced oil consumption from 1.5 qts in 5000 miles to zero qts./5000 miles. It cleans out the rings etc. very effectively. Do not use a "shock" solvent such as gunk etc. as it can clog oil passages. autorx works slowly to remove deposits.


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## Mr Roo (Aug 8, 2006)

*Re: how much diff between 15w 40 and 10w 40 (saaber2)*

I have never heard of autorx? is this some type of cleaner or additive?In my case, 10w 40 would be the next "thicker" oil over my usual 10w 30 correct? I would go to the 10 w 40 before going to the 15w 40?


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## saaber2 (Jul 15, 2008)

*Re: how much diff between 15w 40 and 10w 40 (Mr Roo)*

autorx is an ester and lanolin based cleaner that slowly dissolves sludge carbon etc. in the engine. It works and is not snake oil. It doesn't fix every problem obviously but if the oil consumption is related to dirty ring packs, it will help. If the cylinders or rings are actually "worn out", it won't help. Google autorx to find it.
5W40 and 10W40 and 15W40 are going to be about the same viscosity at operating temp. Cold temp viscosity would be different though. 5w40 will give better cold temp viscosity but will likely thin out more than a 10w40, everything else being equal. But it really totally depends on the specific brand and formulation. If you run the auto rx and oil consumption is not reduced then a thicker oil may help. If your engine is super sludged up, one dose of autorx may not clean enough.


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## tjl (Mar 24, 2001)

*Re: how much diff between 15w 40 and 10w 40 (Mr Roo)*


_Quote, originally posted by *Mr Roo* »_None vw related. Older turbo volvo that is starting to use oil. currently use 10w 30 sythetic since owned. I was told to go to 15w 40 but see 10w 40 as well. I thought 15w 40 was diesel oil, but correct me here. Explain the diff to me. 

15W-40 is a common grade for conventional oils made for diesel engines, although these oils commonly carry API ratings for gasoline engines. Synthetic oils for diesel engines often come in 5W-40.
What year and model is your car? volvocars.com has owner's manuals for some older cars; they may contain a nice little chart of oil grades for various temperatures. Something like this:








http://apps.volvocars.us/owner...#pg92


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## dubbinmk2 (Jan 15, 2008)

*Re: how much diff between 15w 40 and 10w 40 (tjl)*

run 10w40 and call it a day....


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## mekelbreg88 (Jul 13, 2009)

the 10w- and the 15w- are the oil's weight when the oil is cool/below operating temp. the -30 or -40 is the oils weight wen the oil is at operating temp (the w stands for 'winter' (cold))
hope that helped...


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