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0w-40 or 5w40?

Old 10-21-2012, 07:44 PM
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Default 0w-40 or 5w40?

I just went to a new shop for an oil change. They recomended I switch from 0w-40 to 5w-40 due to the milage of my MSRT. I am at 65k. Does anyone out there have any thougts on this?
Old 10-22-2012, 01:09 AM
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Join Date: Mar 2006
Location: Norcross GA
Posts: 8,114

if the manufacture the people who designed your engine wanted that weight oil to be put in a a certain mileage it would be posted in your owners manual .
Old 10-22-2012, 08:18 PM
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Location: Fraser Valley
Posts: 103

The guys at that shop are idiots. They clearly don't understand how the viscosity of an engine oil is rated.

Although the 5W-40 oil may pour marginally slower out of the bottle (than the 0W-40), that does not mean that it is a thicker oil at operating temperature. (This is probably about as far as their thinking goes).
The operating temperature viscosity is rated at 100C (210F) and a 40 weight oil can be anywhere from 12.5 - 16.29 centistokes (cST). The point being is that the rating is a range - it is not one specific thickness (or viscosity).

Without knowing what brand/flavour of oil you are running & what the garage wants to use it is impossible to say which is "thicker." Difference in base stocks, additives, etc. will alter the characteristics of an oil. I won't even begin to attempt to touch the subject of mineral (group II) vs. synthetic (whether it be group III, IV, V).

Remember... the upper number is the more important number. Whether you run 0W-40, 5W-40, 10W-40, 15W-40 - at operating temperature they will all be similar in viscosity. This doesn't mean that you can/should run any of the oils in your engine - if the manufacture recommended 5W-40... then in your location, a 15W-40 could be too thick in freezing weather and cause lubrication starvation issues at start-up.

I agree with Kevin - the manufacturer would have had a sliding scale for viscosity based on mileage if it was warranted.

No oil (doesn't matter if it is $2 bargain store or $20 exotic oil) will fix a worn out engine (at 65K yours should not be anywhere near being worn out). And stay away from additives - they are a bandaid at best and usually they only accomplish in making your wallet thinner.

Find yourself a new shop.

Personally, I change my own oil (I know not everyone can or wants to) or I use an intelligent independent mechanic if the situation requires.
Quick lubes are on my do not visit list.

/rant off
Old 10-23-2012, 06:12 AM
Join Date: Aug 2012
Location: Florida
Posts: 40

Stay with the factory spec oil. And using synthetic will definitely extend the life of the motor due to its superior protection during cold start when most of the wear occurs.

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