Another "Best Oil" question

[glundblad]

Sorry to start another "Best Oil" post. Dino verses synthetic has been beaten to death in other posts so I won't go there and regarding Wal mart, Don's is better than mine ;) . The general consensus from previous posts is that today's oils are not designed for our engines due to low zinc & phosphorus which is required for flat tappet engines.

 

That being said, I was curious what everyone thought about running 50 weight oil in a 4.0 ? Mobil 1 15w-50 to be exact. The manual always said 30 or 40.

 

I ran across the following chart and Mobil has an oil designed explicitly for flat tappet engines. I thought that was very interesting. Plus, this oil has very high zinc & phosphorus. I notice it is SM rated rather than SL:

 

(It is about 3/4 down on the first page)

http://www.mobil.com/USA-English/MotorOil/Files/Mobil_1_Product_Guide.pdf

 

Do you think I am hard on it if I run 15W-50?

[ComancheKid45]

According to the other thread anything that is API-SM rated doesnt contain the amount of zinc they our engines would enjoy...API-SL is apprently an older standered and still is considered alright for the 4.0.

[rcturgeon]

i keep hearing stuff about the 4.0 but what about the 2.5 should i still try to find some zinc and phosphorous containing oil

[whowey]

Sorry to start another "Best Oil" post. Dino verses synthetic has been beaten to death in other posts so I won't go there and regarding Wal mart, Don's is better than mine ;) . The general consensus from previous posts is that today's oils are not designed for our engines due to low zinc & phosphorus which is required for flat tappet engines.

 

That being said, I was curious what everyone thought about running 50 weight oil in a 4.0 ? Mobil 1 15w-50 to be exact. The manual always said 30 or 40.

 

I ran across the following chart and Mobil has an oil designed explicitly for flat tappet engines. I thought that was very interesting. Plus, this oil has very high zinc & phosphorus. I notice it is SM rated rather than SL:

 

(It is about 3/4 down on the first page)

http://www.mobil.com/USA-English/MotorOil/Files/Mobil_1_Product_Guide.pdf

 

Do you think I am hard on it if I run 15W-50?

 

 

Any question regarding the viscosity of oil you are using has quite a number of inputs into it that you haven't detailed here. Usage, environment and operating conditions are three of the major ones.

 

Now when considering a multi-viscosity oil with a large differential, you need to be mindful of the additives in it. In a correctly operating engine, it is normally the additive package that wears down rather than the basestocks. The basestocks can be damaged by extreme operations, low quality, or abnormal occurrences(fuel dilution, coolant contamination, exhaust gases, etc.). The issue comes to the front when a particular oil has a relatively large amount of one type of additives. In this case a large amount of viscosity modifiers. 1 qt. of 15w-50 will have a larger quantity or more aggressive viscosity modifiers than a similar quart of 15w-40. Normally I don't like to run anything with a large spread, and I don't generally recommend my customers do it either.

 

Now for the chart... An oil can still have above 800ppm of Zinc and still be SM rated, IF it is a diesel oil and carries the CJ-4 rating before the SM on the label. So one of three things has occurred with that chart.

 

1. They left off the CJ-4 rating

2. Its really API-SL rated and the SM was a mistake

3. It doesn't have that high of a level of Zinc or Phosphorous.

[whowey]

i keep hearing stuff about the 4.0 but what about the 2.5 should i still try to find some zinc and phosphorous containing oil

 

For the purposes of this discussion... the 2.5l requirements are the same as the 4.0l requirements. You still have a flat tappet camshaft motor and there lies the concern.

[rcturgeon]

i keep hearing stuff about the 4.0 but what about the 2.5 should i still try to find some zinc and phosphorous containing oil

 

For the purposes of this discussion... the 2.5l requirements are the same as the 4.0l requirements. You still have a flat tappet camshaft motor and there lies the concern.

 

 

thanks i wanst sure but i figured as much diesel oil here i come