Inside motor oil

in comparing the 2 oils :

VR1.....10w-30 conventional

VR1......20w-50 conventional.

My first question is this:

If 100c =212 degrees

If 40c =104 degrees

This of course has nothing to do with outside temps.. If I am correct, then what temps are they taking? engine?
_____________________________________________________________________

{I have some numbers regarding these 2 oils,I just want to make sure I have this correct to start with...

Yes and no. Generally the outside conditions will influence what viscosity you should run, but the oils are rated based on actual oil temps (0 degress and 212 degrees). In most conversations you are correct the outside temps will influence the decision, because it affects the first number(cold start temps). If you're in Canada obviously you want a lower first number because the colder it is the harder it is for the oil to flow vs. FL where its always hot and your oil is bound to be 70-80 at startup. But excluding extreme weather conditions the majority of an oils life will be spent at operating temps(2nd number) and oil weight choice should be driven off load and oil temp ratings instead of outside temp(within reason obviously).


Number before the W is the cold start viscosity, the number after the dash is the running temp viscosity. The higher the number the more resistant the oil is to thin out(2nd number). So the 20w-50 will not flow quite as well when starting up, but will have better resistance to thinning at operating temps.

In your boat the more important piece of info is going to be the zddp content. I thought I saw a post showing that there was a higher content in one of the viscosity ranges, though I could be wrong.

Foot Fungus------------


Yes ZDDp is higher in VR1 Conventioal 10w-30 and 20w-50

          Then that if Vr1 synthetic of same weight.

Conventional around 1400 both ZINC and Phos
Synthentic     around 1100 zinc and phos.

I posted this back on another thread about 3 days ago...

not something I've ever considered relevant   

VISCOSITY INDEX...Empirical number which indicates the rate of exchange in viscosity of an oil within a given temperature range.

They claim the higher the number the better. keeps your bearings happy they say.

Now see the chart for VR1,,See where they Say viscosity index 143 for 10-30 132 for 20-50..

But in temp ranges higher numbers are given to the 20-50 vs the 10-30.

I see the test are run in certain temp ranges,,,

Yet ......... Viscosity index says higher for 10-30?

ty lakeskier.


See the numbers on the VR1,, from Valvoline..

I am confused they say the higher the number in In the VISCOSITY index the better.. 10-30 has a higher number next to Viscosty index.

The 20-50 has higher numbers in diff temp ranges...

Wonder what number to use..

The number next to--VISCOSITY Index or the other Numbers?

Ty again for responding....

Lakeskier ..Ty again!

I understand better...

I myself and a family member[brother prefer the lower number 10w30 vs 20w-50.. I see many who like the 50.. Mr,Peter is one of them..

I could not get a answer as to why from him, I decided to learn about oil and diff weights of oil...

He just said -50 is better, and then took off for the HILLS on me...

Ty again for your time... Lake skier....

eljayrx wrote: Lakeskier ..Ty again! I understand better... I myself and a family member[brother prefer the lower number 10w30 vs 20w-50.. I see many who like the 50.. Mr,Peter is one of them.. I could not get a answer as to why from him, I decided to learn about oil and diff weights of oil... He just said -50 is better, and then took off for the HILLS on me... Ty again for your time... Lake skier....

LaurelLakeSkier wrote: This is oversimplifying but if you just look at the numbers - 10W30 has a factor of 3 between the numbers. So when the engine starts cold, the oil acts like SAE10 but when at operating temp, the oil has thinned out to be "act like" to SAE30. The 20W50 has factor of 2.5 since with the oil having the thickness of SAE20 when cold and thinning to 50 at operating temp. The viscosity index is a measure of how much the thickness CHANGES not how thick or thin the oil is.

Sorry Lin but with all your searching on oil, I thought you would understand the concept on multi weights. Mark (Yes, his name is MARK!!!!) explained it pretty good.

BTW, I have been holding back on commenting about oil. We have been though the issue so many times!! I told you before, just have your brother take over for you. Don't ask us again.

From reading on this site, I understand that boat engines have higher internal temps (including oil) than car engines, due to the constant heavy load. This is in spite of the lower cooling water temp. Therefore, the heavier weight can help guard against oil thin out.