Is 0w20 always interchangeable with 5w20?

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I'll play devils advocate. Using two engines; Chrysler's 3.5l HO V6 and Honda's 2.2l I4. Both of these engines, even until their last days, 2011 for Chrysler and 2009 for Honda, recommended 10w30 over 5w30. Chrysler said 5w30 COULD be used IF temperatures below freezing were expected ONLY to aid in cold start. There's got to be a reason some manufacturers have these recommendations on certain engines.
 
Hmm. I can't think why, unless at the time the vehicle documentation was written the manufacturer was unaware of an oil of that rating meeting the required spec?
 
Since GM 4718M (Corvette spec) existed around 1992, I cant see Chrysler ignoring 5w-30 if it was ideal, especially in light of CAFE regulations. Oil meeting that spec is mighty tough. I don't know why I bother posting anymore. Someone with a strongly held ill-informed opinion will follow with a snarky comment. fwiw.
 
My 2010 3.5 H.O. in my Challenger calls for 10W instead of 5W, so I wouldn't assume that 0W would substitute for 5W. FWIW I use 10W-30 in my Silverado also, which calls for 5W. I don't think it's an extremely big deal, though.
 
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Originally Posted By: 95busa
Since GM 4718M (Corvette spec) existed around 1992, I cant see Chrysler ignoring 5w-30 if it was ideal, especially in light of CAFE regulations. Oil meeting that spec is mighty tough. I don't know why I bother posting anymore. Someone with a strongly held ill-informed opinion will follow with a snarky comment. fwiw.


Well why wouldn't someone comment....you seem to be using logic and reason and not even a hint of conspiracy theory!
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A guy here at work has a 2010 3.5 spec'd for 10w30, never understood that. Not sure what their reasoning could be.

Back OT, I have always thought of 0wXX as interchangeable with 5wXX or 10wXX and I would almost bet that one of those Chrysler 3.5s would turn in good UOAs on 0w30. Likely live a long happy life. Of course I'm not a Chrysler engineer and could be very wrong. It is too bad manufacturers don't have to publish information on some of their requirements.

I would think in most engines it is a fine substitute though.
 
Originally Posted By: Silverado12
My 2010 3.5 H.O. in my Challenger calls for 10W instead of 5W, so I wouldn't assume that 0W would substitute for 5W. FWIW I use 10W-30 in my Silverado also, which calls for 5W. I don't think it's an extremely big deal, though.


AH but would 10wXX always substitute for 5wXX?

Do you have any UOAs on your 3.5? Curious if it has a tendency to shear.
 
The answer is no especially when it comes to OEM 0W-20s that have a very high viscosity indexes of nominally 220.
For example, while Toyota has back-spec'd their 0W-20 many years for most models, some older vehicles are spec'd for 5W-20 and not 0W-20.

The following is a quote of mine from another recent thread that includes the explanation as to why:

"A high viscosity index is generally better as long it is retained in service. And one should not consider an oil's VI without also knowing it's HTHSV. Why? Because the greater the VI difference, the lighter the higher VI oil will be, not only as one would expect on start-up but also at normal operating temp's for a given HTHSV.
For example, TGMO 0W-20 (VI 216) is much lighter on start-up than PYB 5W-20 (VI 150) but it is also somewhat lighter at normal operating temp's (say 90C) although both oils gave the same 2.6cP HTHSV. So if you want to maintain the normal operating viscosity with TGMO as you would have with PYB you'll have to increase it's HTHSV to about 2.7cP. How? One easy way is add a pint of M1 0W-40 . You'll lower the VI of the TGMO to about 210 but it will still be much lighter than PBY 5W-20 on start-up, have the same normal operating viscosity with the added benefit of a higher HTHSV rating for the parts of an engine that get very hot."

All that said, there are lots of people running TGMO 0W-20 and even the lighter Sustina 0W-20 in vehicles just spec'd for the 5W-20 grade without issue, but they are running a somewhat lighter than specified oil.
Of course if your vehicle is equipped with an oil pressure gauge then you'll know first hand how much lighter any particular 0W-20 is vs a 5W-20 and in most applications (but not all) the lightest 0W-20 it still more than heavy enough.
 
Originally Posted By: CATERHAM
The answer is no especially when it comes to OEM 0W-20s that have a very high viscosity indexes of nominally 220.
For example, while Toyota has back-spec'd their 0W-20 many years for most models, some older vehicles are spec'd for 5W-20 and not 0W-20.

The following is a quote of mine from another recent thread that includes the explanation as to why:

"A high viscosity index is generally better as long it is retained in service. And one should not consider an oil's VI without also knowing it's HTHSV. Why? Because the greater the VI difference, the lighter the higher VI oil will be, not only as one would expect on start-up but also at normal operating temp's for a given HTHSV.
For example, TGMO 0W-20 (VI 216) is much lighter on start-up than PYB 5W-20 (VI 150) but it is also somewhat lighter at normal operating temp's (say 90C) although both oils gave the same 2.6cP HTHSV. So if you want to maintain the normal operating viscosity with TGMO as you would have with PYB you'll have to increase it's HTHSV to about 2.7cP. How? One easy way is add a pint of M1 0W-40 . You'll lower the VI of the TGMO to about 210 but it will still be much lighter than PBY 5W-20 on start-up, have the same normal operating viscosity with the added benefit of a higher HTHSV rating for the parts of an engine that get very hot."

All that said, there are lots of people running TGMO 0W-20 and even the lighter Sustina 0W-20 in vehicles just spec'd for the 5W-20 grade without issue, but they are running a somewhat lighter than specified oil.
Of course if your vehicle is equipped with an oil pressure gauge then you'll know first hand how much lighter any particular 0W-20 is vs a 5W-20 and in most applications (but not all) the lightest 0W-20 it still more than heavy enough.





What happens to people who took your comments early on as in a year ago or so ago and ran out and bought the high VI 0W20 oils for their Ford, and Chrysler products calling for 5W20? Just a question that's all, no flaming or attacks intended. Lot of people were doing it I think. Not every one has an OP gauge a lot have stock idiot lights.
 
demarpaint, a number of members like yourself have PM'ed me over the years looking for a particular recommendation and yes I have and continue to recommend high VI 0W-20's for specific applications where the grade has not been specified.

Would I recommend TGMO 0W-20 for someone with a Mustang GT for which the heavier than average semi-syn Motorcraft 5W-20 is specified and is planning on taking their car to the track? No, although if they really wanted to run a high VI oil I'd suggest thickening TGMO to match the hot operational viscosity of the spec' 5W-20. Use of an OP gauge is the only practical way to do that.
 
Originally Posted By: pbm
If a vehicle specs 5w20 can 0w20 always be used..(out of warranty of course)?

In warranty, out of warranty, doesn't matter. The answer is yes.
 
Originally Posted By: CATERHAM
demarpaint, a number of members like yourself have PM'ed me over the years looking for a particular recommendation and yes I have and continue to recommend high VI 0W-20's for specific applications where the grade has not been specified.

Would I recommend TGMO 0W-20 for someone with a Mustang GT for which the heavier than average semi-syn Motorcraft 5W-20 is specified and is planning on taking their car to the track? No, although if they really wanted to run a high VI oil I'd suggest thickening TGMO to match the hot operational viscosity of the spec' 5W-20. Use of an OP gauge is the only practical way to do that.


I got it. It is however more recently that you're recommending the CATERHAM blend, when we chatted years back you weren't recommending the blend. That is what prompted my question that's all.
 
Yes, adding a small amount of M1 0W-40 came about to address the concerns of some members about using the light high VI 0W-20 oils for more severe use like summertime trailer towing etc.
Even though these shear stable 0W-20 oils more than likely still have an adequate viscosity reserve, bumping the HTHSV to 2.7cP or even higher is good for piece of mind even if technically unnecessary and of course it won't raise the start-up viscosity of the oil much at all.
 
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