V10 Motor Oil

PapPappy wrote:
The lighter lube oil is because they are making the clearances tighter, so I'd stick with what they tell you to use...more viscous lube oil will have a harder time getting through the bearings, which would defeat your purpose of making sure you have proper lubrication for those hills you are climbing.

I'm not positive, but the lighter lube may also cool faster, because it can flow easier, which is a good thing too!

If you want to try and improve things, you might want to check into a synthetic oil....and maybe see if there is an additive (Slick 50 type stuff) that the Mfgr. allows or recommends. If they say NO, then I'd stick with what they say, until the warranty is long gone.

Tolerances are tighter but not the MINIMUM clearance of a bearing of a typical size. However, because of tighter tolerances, the maximum clearance possible, in production, has been reduced. That allows a lighter oil to be used---------and provides small mpg increases in lighter vehicles.

From a post in another thread this week:


A typical journal bearing of a certain diameter, width and operating rpm well have a minimum allowable operating clearance (let's say that minimum CLEARANCE is .001 inch). Then let's say the minimum machining TOLERANCE for the bearing ID and for the shaft OD EACH is +/- .003 inch.

For a nominal 2" rotating shaft and bearing, the shaft will be spec'd something like 1.997" to 2.003". Thus the bearing will need to be spec'd to be from 2.004 to 2.010 to provide a minimum or .001 operating clearance with the smallest bearing going on the biggest shaft.

Now if tolerances can be reduced to +/- .0015 inch, the shaft can then be spec'd to 1.985 to 2.0015 and the bearing can be spec'd to 2.0025 to 2.0055. The minimum clearance is still .001" but the maximum clearance has been reduced from .013" to .007"----------which allows (but does not require) a thinner oil.

Both scenarios, however, require an oil "thin" enough to provide lube when things are at their tightest----------at cold start up.

At cold start up all oils are considerably thicker (by many times) than what they are at operating temps. Some typical viscosities (cSt) of Mobil 1 oils are:

Temp------5w-30------15w-50

-20----------6284--------21,852
0------------2129---------6462
25------------697---------1836
32------------531---------1348
50------------281----------657
100------------71----------138
150------------27-----------46
175------------18-----------30
200------------13-----------20
225------------10-----------15
250-------------7.6---------11.1


Please know that a 5w-20 oil will be very similar to the 5w-30 oil at cooler temps but drop to single digit viscosities at around 212 degrees F -------------which may be fine with a bearing and shaft machined to tight tolerances. This will also improve mpg during CAFE testing.

However, that close tolerance bearing was also fine with viscosities of several hundred when the engine was starting and warming up-----------and even several thousand if you live in the North.


Bottom line, a 5w-30 oil (or even a 5w-40) will do no damage to your engine where a 5w-20 oil is recommended. It may reduce your MPG by a small percentage, however. It will also provide more lubrication strength under heavy load and at higher temps.

My V10 often runs with the engine temp between 200 and 212 degrees (scan gauge). As I want it to last a long time, I will sacrifice 0.1 or 0.2 mpg to be sure it does.