Motorcraft Diesel 5w-40 Full Synthetic in flat tappet engine?

[CleverUserName]

I've always been told "if you need to add an additive to your oil, you're not running the right oil", so I'd prefer to stick with my Amsoil Zrod 10W-30.

The only benefit in using a 5w vs 10w is in extreme cold. If you are starting your car in -10F or colder ambient temps the 5w will be easier for the oil to flow but if you’re not in extreme cold it doesn’t matter. If the oil is liquid and pumpable a 5w, 10w and even 15w will all flow the same through the engine although the pressures will be different.

If you don’t need a 5w then the Zrod is fine, use it. I prefer 10w30 in my cars as I live in California and it works in everything here as the climate is mild. I only use 5w40 in my truck.

 

[fantastic]

Last I checked, ford only recommended their motorcraft oil and said ck-4 was inadequate for whatever reason. That was a while ago though. I'm not sure what their stance is now on it.

There are now many 10w-30, 5w-40, & 15w-40 HDEO's that are "Approved" or "Meets" Ford WSS-M2C171-F1. That is what Ford wants in the Power Stroke's.

Here's just a few to start:

Post in thread '1997 F250HD 7.3 Powerstroke'

Jun 6, 2024

15 quarts
You'll want to use an oil that's "Approved" for or "Meets" Ford Specification WSS-M2C171-F1
You can find that on :

• Mobil Delvac Extreme 15w-40
• Rotella T4 & T6 15w-40
• Chevron Delo XPS 15w-40
• Super Tech 15w-40 "Conventional" & they have a newer "Full Synthetic" version I did a VOA on HERE
• Castrol GTX 15w-40
• Traveller at TRACTOR Supply 15w-40
• Oreilly's Auto 15w-40
• Fram at Advance Auto 15w-40
• Sinopec Synthetic 15w-40 <---I've run it with success.

I don't have any problems using an oil that says it "Meets" that...

• fantastic

• 

 

[OVERKILL]

Some good information on this subject starting with this post:

Post in thread 'Zinc Content'

Dec 4, 2024

As stated above, pay attention to the phosphorus content. Zinc dialkyl-dithio-phosphate (ZDDP) is the anti-wear additive in question when someone mentions "zinc" for engine oil. People colloquially shorten it to just the first part "zinc" though this has caused some confusion. It's actually a family of additives with nearly 200 different variants of ZDDP, not all created equal and with a rather wide range of reactivity and function. It's comprised of the elements zinc, phosphorus, and sulfur with various branching and chaining of various alkyl groups that dictate how the additive acts...

• RDY4WAR

• 
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[Slick]

https://www.ford-trucks.com/forums/1735563-bad-oil-report-with-motorcraft-5w40-synthetic.html

I'm pretty sure Blackstone measures Zinc by PPM. In the link above, somebody sent a used oil sample out of their 7.3 PowerStroke to Blackstone Laboratories and the test shows the "Universal Averages" for zinc at 1267. Yes I see the title says "bad oil report" but I'm pretty certain that it has more to do with the engine the oil came out of.

If the 5W-40 will work, I'm going to buy the Motorcraft oil not just because I have a discount but there's also no wait time to acquire it. Since I work at a dealership, that pretty much always has it in stock, it's available for me at any time. I'm kind of tired of ordering oil and I don't know anyone where I live that distributes P66.

DG

I use 10W-30, 5W-40, and 15W-40 HDEO in my outdoor power equipment engines, diesel tractors, Ram/Cummins 6.7 and older truck/auto gasoline engines that have the Ford Specification WSS-M2C171-F1 to assure the oil has the higher ZZDP.

Many times I buy the Motorcraft brand oil since it is in a 5 quart container versus other HDEO brand oil that comes in 4 quart jugs so often it is a lower cost per quart.

All of our local Walmart Stores sell the the Motorcraft Brand 5 Quart Jugs of 10W-30 and 15W-40 for $25.88 plus sales tax. I do not see the Motorcraft HDEO it at local Walmarts in 5W-40 viscosity. Likely since the current 6.7 Powerstroke specs 10W-30 and 15W-40.

Slick

 

[johnmyster]

All of our local Walmart Stores sell the the Motorcraft Brand 5 Quart Jugs of 10W-30 and 15W-40 for $25.88 plus sales tax. I do not see the Motorcraft HDEO it at local Walmarts in 5W-40 viscosity. Likely since the current 6.7 Powerstroke specs 10W-30 and 15W-40.

Slick

It’s actually been awhile since powerstokes have specified 15w-40. 5w-40 is the 6.7’s specified lube for severe duty.

Some engine builders theorize that spun main bearings in the early 6.7s (which had tighter clearances) were a product of folks in cold climates using 15w outside of ford’s specification.

It’s crazy that the F1 specified minimum of 1000 ppm is considered “high.” Would’ve been considered weak sauce 15 years ago. Then again, ULSD and lower oil detergent contents tell the whole story.

 

[Redhawk454]

I've seen only a few Black Stone Lab tests on this oil and it pretty consistently has above 1200 ppm of zinc and 1150 ppm of phosphorus. The problem is because it's a diesel oil, the detergents could potentially wipe the zinc off the cam lobes. I ran the 10w-30 version of this oil in an old 400 Ford that had an RV cam from the 80s or 90s and the engine didn't care. With these new cams though you have to be pretty cautious.

I mean, this is true with any motor oil where different additives are competing with space on the metal regardless of it being diesel or gas motor oiL.

 

[addyguy]

I’m curious about what this 400 is in…?