Hey,

Im new the forum and ive seen alot of back and forth with 0W-40 and 5W-40, well i just clicked over to 150,000 miles and what would be the best oil to run to get ready for summer, the motor doesnt have no ticks or anything, so what do you all think????

 

The engines in these cars are "rock solid" if the routine maintenance has been done consistently throughout the years along with normal wear & tear. To comply with factory recommendations, either one of the grades would be applicable, my opinion. With the mileage you're stating on your car, I would probably lean towards the 5w40 version - that's just me talking out loud. Both oils would provide the same level of protection & lubrication at normal engine operating temperatures. The 5w40 version would give your some added protection (increased viscosity & potential lubricity) at start-up & engine warm-up period considering the mileage on the engine which could have increased tolerances ever so slightly over the years.

 

I can go along with that, I certainly have increased tolerances over the years

 

NOT ME!! I've got a pretty "short fuse" when it comes to tolerances!!

 

Parts are made to sizes which have tolerances, when used for some time the parts can exceed the original tolerances and that is called wear
at this point the parts are out of tolerance.
Do not confuse tolerance with wear.

 

I didn't - Increased tolerance (dimensional change) would be the same as wear when compared to original specs. You just stated it more definitive. Thanks for clarifying.

 

new here but my 07 crossfire has 125k miles on it and i use royal purple ow40 good for 5k miles great oil for the 3.2 motor

 

If you put an oil pressure gauge on the engine, you will never put 0W40 in there again. (Exception would maybe be a short-commuter in winter.)

5W40 is the MB recommendation since around 2011 and that's what I run. Back when I was running the Graphite really hard in hot, Georgia weather, I went with 5W50 - but it was pretty heavy below around 60F.

Every approved oil is on this list - the list changes over time, but right now, here is what MB says - notice the emphasis on 5W40:

https://bevo.mercedes-benz.com/bevolisten/229.3_en.html

 

I think that using the oil pressure gauge to decide what oil grade to use is not of any great use.
You have stated before that the pressure goes up as the revs increase, this is to be expected as the pump cannot push the same volume of oil through the small clearances and holes at the same rate as it can when the revs are lower. This is because the clearances and holes have not changed while the volume of oil that is trying to be pushed them has increased in proportion to the increase in revs, ignoring small inefficiencies, therefore the back pressure increases and the oil gauge gives a higher reading. Having a high reading could mean that insufficient or no oil is being pumped through the small clearances only through the holes because the oil is too thick.
What you want is oil able to get through the small clearances no matter the temperature of the oil and engine. Also the oil must be able to adhere to the surfaces under load and not get squeezed out.
A basic understanding of the SAE viscosity numbers is a good start.

 

In general, I do not disagree, Dave. In fact, the specification for our engines is for "3 pounds or more" oil pressure at engine idle at 205F. (My engine never gets above 195F but I still saw pressure of 5-6 pounds with 0W40.) And I would never put 20W50 or even 10W40 in this engine (altho MB does approve of a few 10W40s in 229.3.)

From my perspective, 5 weight oil is pretty damn thin. For the vast majority of the time the engine is running, lubricating oil is meant to keep bearings in suspension at 200F (or higher), I simply do not agree with 0 weight oil in most cases. When I started driving, 10W30 was the most commonly sold and used product out there, my new truck in 1993 specified 10W20, which I ran up to 10,000 miles. After that, I went to 15W40 and after 100,000 miles, I went to 20W50. That engine is still on the road, at over 460,000 miles (actually, it was taken off the road due to rust in the last several years - but it is still used to haul wood around a farm). The block, valves, crank, rods and rings are original. And yet, I was told I'd ruin the engine if I went past 10W30.

I do admit that engine startup wear is a concern - but I am not one who leaves my vehicles outside, and I tend to let them warm up before driving when the temperature is below even 50F.

I'd like to see you expand on that. I've read a lot about SAE multi viscosity ratings, and a lot of what is published is contradictory.

 

The following is a good explanation of oil viscosity ratings by SAE (Society of Automotive Engineers:

The Society of Automotive Engineers (SAE) has established a numerical code system for grading motor oils according to their viscosity characteristics. SAE viscosity gradings include the following from low to high viscosity: 0, 5, 10, 15, 20, 25, 30, 40, 50 or 60. The numbers 0, 5, 10, 15, 20 and 25 are suffixed with the letter "W", designating they are "winter" (not "weight") or cold-start viscosity, at lower temperature. The document SAE J300 defines the viscometrics related to these grades. Kinematic viscosity is graded by measuring the time it takes for a standard amount of oil to flow through a standard orifice, at standard temperatures. The longer it takes, the higher the viscosity and thus higher SAE code.

Single-Grade Oils - A single-grade engine oil, as defined by SAE J300, cannot use a polymeric Viscosity Index Improver (also referred to as Viscosity Modifier) additive. SAE J300 has established eleven viscosity grades, of which six are considered Winter-grades and given a W designation. The 11 viscosity grades are 0W, 5W, 10W, 15W, 20W, 25W, 20, 30, 40, 50, and 60. These numbers are often referred to as the "weight" of a motor oil, and single-grade motor oils are often called "straight-weight" oils.

Multi-Grade Oils - The temperature range the oil is exposed to in most vehicles can be wide, ranging from cold temperatures in the winter before the vehicle is started up, to hot operating temperatures when the vehicle is fully warmed up in hot summer weather. A specific oil will have high viscosity when cold and a lower viscosity at the engine's operating temperature. The difference in viscosities for most single-grade oil is too large between the extremes of temperature. To bring the difference in viscosities closer together, special polymer additives called viscosity index improvers, or VIIs, are added to the oil. These additives are used to make the oil a multi-grade motor oil, though it is possible to have a multi-grade oil without the use of VIIs. The idea is to cause the multi-grade oil to have the viscosity of the base grade when cold and the viscosity of the second grade when hot. This enables one type of oil to be used all year. In fact, when multi-grades were initially developed, they were frequently described as all-season oil.

The SAE designation for multi-grade oils includes two viscosity grades; for example, 10W-30 designates a common multi-grade oil. The first number '10W' is the viscosity of the oil at cold temperature and the second number is the viscosity at 100 °C (212 °F). The two numbers used are individually defined by SAE J300 for single-grade oils.

 

Thanks for the info.

 

a great source for understanding oils & viscosity. Is a web site called
Bobistheoilguy.com