PDA

View Full Version : Oil Viscosity



RedDog
04-08-2006, 08:55 PM
I have about 5 quarts of Valvoline 40 wt and 5 of Valvoline 50 wt oil. If I mix these 50/50 do I end up with an oil of about 45 wt or do I just create a problem? Seems if would be fine. I normally run the straight 40 but ....

hardcrab
04-08-2006, 09:10 PM
no, don't mix oil viscosities (?)
that's not how it works ,

Barry Eller
04-08-2006, 09:12 PM
I have about 5 quarts of Valvoline 40 wt and 5 of Valvoline 50 wt oil. If I mix these 50/50 do I end up with an oil of about 45 wt or do I just create a problem? Seems if would be fine. I normally run the straight 40 but ....
You are correct as long as the oil you are mixing is straight weight oil. Do not
mix multiviscosity oils. The formula must be 50/50 to achieve 45 weight.
Those are thick oils to use unless you are turning extremely high rpm's or have a tired engine that needs oil that thick.
30 weight oil is recommended by most manufactures of marine engines. I use 30 weight (Dino) oil, not synthetic, because I have a roller cam in my 502. Bob Teague, from Powerboat magazine wrote that synthetic oil is too slippery and makes rollers slide instead of roll, causing premature wear on camshaft lobes.
Anyway, I change my oil every 25 hours.

Pismo
04-09-2006, 06:32 AM
Read

http://www.offshoreonly.com/forums/showthread.php?t=107808&page=1&pp=20



Everything you will ever need or want to know about oil and filters including the Teague idea.

Barry Eller
04-09-2006, 06:50 AM
Pismo, that is a lot of good information. I use Mobil 1 in my Mustang GT and my Chevy truck. I have about 15 hours on my new 502, I have changed the oil twice. I think where people get into trouble is NOT changing oil and filter, or not checking their oil.
What do you use in your boat, and how often do you change your oil?

joseph m. hahnl
04-09-2006, 08:27 AM
I'm going to throw something into the equation that is not thought about when selecting viscosity number. I have read pretty much all of the threads on this topic and it is clear that straight 40 is what is recomended by merc.
"You OMC guys need to put some input" in multi it is 20/40. 20/50 is 2nd choice but allowable. So here it is most marine engines run raw water thru the engine this keeps the engine realativley cool. then there is a half cooler which cools the engine block with coolant, and chills the exhaust manifold and exhaust gas with raw water. Then there is the full cooler. "This is what I have". The full cooler uses coolant in the engine block and the exhaust manifold. The raw water only cools the exhaust gas. "NOTE in both systems
the cooler itself has 2 tanks one with hot coolant the other with cold raw water which disipates" the heat out thru the exhaust gas.

I have found that the closed cooling runs extremely hot."This is where you don't want to be with out viscosity. Using low number will burn the oil very quickley.

So my point is you need to consider operating tempreture of you engine
at all ranges not just at full throttle. My 350 mag runs cooler at WOT than it does at Idle. More raw water flowing thru the cooler creates more disipation of heat.


AS allways Food for thought.



joe

CHACHI
04-11-2006, 07:28 PM
I have about 5 quarts of Valvoline 40 wt and 5 of Valvoline 50 wt oil. If I mix these 50/50 do I end up with an oil of about 45 wt or do I just create a problem? Seems if would be fine. I normally run the straight 40 but ....First , it would be ok to mix the two. The chemistries are similar. Second, you will not have a 45 wt oil. The SAE does not recongnize a 45 wt. What you will have is either a heavier 40 or a thinner 50, it all depends on the viscosity of each oil at 210 degrees when new before you mix them. Ken

CHACHI
04-11-2006, 07:32 PM
You are correct as long as the oil you are mixing is straight weight oil. Do not
mix multiviscosity oils. The formula must be 50/50 to achieve 45 weight.
Those are thick oils to use unless you are turning extremely high rpm's or have a tired engine that needs oil that thick.
30 weight oil is recommended by most manufactures of marine engines. I use 30 weight (Dino) oil, not synthetic, because I have a roller cam in my 502. Bob Teague, from Powerboat magazine wrote that synthetic oil is too slippery and makes rollers slide instead of roll, causing premature wear on camshaft lobes.
Anyway, I change my oil every 25 hours.Barry, if the roller is sliding on the oil film, whats causing the flat spot? Parts are suppose to be kept apart by an oil film, so if the part is sliding on the oil film how can a flat spot happen? Ken

CHACHI
04-12-2006, 05:20 AM
Barry, I almost forgot............HD up until 5 or so years ago did not recommend a synthetic for the exact same reason. The crank rollers "slid" causing flat spots. HD now has their own synthetic oil, and they still have a roller crank. Ken

RedDog
04-12-2006, 06:54 AM
I have about 5 quarts of Valvoline 40 wt and 5 of Valvoline 50 wt oil. If I mix these 50/50 do I end up with an oil of about 45 wt or do I just create a problem? Seems if would be fine. I normally run the straight 40 but ....

Nevermind - moot point based on faulty memory from what I thought I had left over from last year. Turns out it was 9 of the 40 and 1 of the 50 so the oil change used all 40 wt

Barry Eller
04-12-2006, 09:22 PM
Barry, I almost forgot............HD up until 5 or so years ago did not recommend a synthetic for the exact same reason. The crank rollers "slid" causing flat spots. HD now has their own synthetic oil, and they still have a roller crank. Ken

HD? is that Harley Davidson? This all goes to show how many opinions there are out there. The important thing is to change oil and filter at regular intervals, depending on how you run you engine.

MOP
04-12-2006, 09:41 PM
Wasn't syn used in some new cars engines right from the factory? I thought I read or heard that, if that is so how do they avoid problems. I may try it in mine may not still doing good dino.

Phil

CHACHI
04-17-2006, 10:29 AM
HD? is that Harley Davidson? This all goes to show how many opinions there are out there. The important thing is to change oil and filter at regular intervals, depending on how you run you engine.Barry, sorry for the gap in the reply, I was picking up my new boat. Yes, the HD is Harley Davidson. Ken

CHACHI
04-17-2006, 10:31 AM
Wasn't syn used in some new cars engines right from the factory? I thought I read or heard that, if that is so how do they avoid problems. I may try it in mine may not still doing good dino.
PhilGM, Dodge, Porsche are all using Mobil 1 as factory fill in some of their cars. Ken

blackhawk
04-17-2006, 04:23 PM
This all goes to show how many opinions there are out there. The important thing is to change oil and filter at regular intervals, depending on how you run you engine.

EXACTLY! When it comes to oil if you ask 10 people you'll get 10 OPINIONS. Kinda like asking an opinion on a supercharger! :D