Ford Powerstroke Diesel Forum banner

5w40? bad?

3K views 11 replies 11 participants last post by  Jmaccal 
#1 ·
I had a guy at the autoparts store call me an idiot for wanting to put thinner oil in my truck for the winter... I useally run 15w40, Well when I was there I was reading the motorcraft superduty oil and it says right on it for temps lower than 20 degrees use 10w-30, A company whoes oil is diesigned for powerstrokes! just wondering what your guys thoughts are? oh yeah he said he has seen 3 trucks blow up cause of thinner oil..
 
#2 ·
Good Question... I also wonder the same..I have 4 gallons of 5w-40 synthetic someone gave me for free-want to run it but unsure! when I start my truck it takes almost 4 secs for the oil gauge to read anything and the red oil light to go out-thought a thinner oil would help? and could it affect the injector pressure?
 
#3 ·
As long as it is diesel rated oil run you wont hurt a thing. Its got to same lube propertys as 15w40. The number before the w is the cold weight the lower the number the better the cold flow.
 
#4 ·
I have run 10,000 miles on 5W-40 rotella without any issues so far. In fact it was probobly the best thing I could have done to my truck for the cold temps. I haven't taken a sample and had it anylized yet, but my gut feeling is Im just fine. In fact when I ran regular dino oil it was getting pretty black by 2000 miles and with the rotella I still pretty clean when I change it at 5000 miles. My recommendation is to run a sample of the oil you are running now and when and if you make the switch take another sample and the proof will be in the report you recieve:thumb:
 
#6 ·
The world is full of self appointed experts....
from the Ford TSB summaries:

6.0 Oil Recommendations:
Some trucks with the 6.0 may exhibit hard starting, rough running and lack of power in cold temperatures, particularly on a cold start. This may be due to the oil being to thick for the operating conditions. Ford is recommending to use the following oils for the listed operating temperature.


SAE 15W-40 is the preferred oil above 30 degrees, but it is acceptable for use down to 10 degrees, and is recommended for towing down to this temperature.
SAE 10W-30 is the preferred weight between -10 to 30 degrees.
SAE 5W-30 and 5W-40 is acceptable for use below 30 degrees, and 0W-30 is acceptable below zero.
(All temperatures are in Fahrenheit.)
The oil used should meet Ford's specification of WSS-M2C171-D or API CI-4 PLUS, CI-4/SL or DHD-1. CH-4 is acceptable for use if CI-4 PLUS is not available. TSB #05-16-6.
Keep in mind that CI-4 oil is designed for the increased soot contamination and higher coolant temperatures of cooled EGR systems on a diesel; CH-4 is not.
Nowhere does the TSB mention synthetic versus conventional oil recomendations or ranges.
Ford has not released anything recommending NOT to use a specific brand of oil.
 
#8 ·
The guy who called you an idiot...is an idiot. That 10w-30 is what Ford tells you to use in the colder months. I have the neat little diesel clinic book that tells me that as soon as temps stay a colder in the winter months its time to make the switch. Its in my truck right and no problems for me...and I have to do a lot of cold starts.
 
#10 ·
DITTO!!!!!! DUDE WAS AN IDIOT!!!!!! Good Post mrnecsteve!!!!
Everyone should know their climate
 
#11 ·
Just to clear the W up, what that means is that the oil flows like X weight oil at 32* F.

So if it says 5w40, it flows like a 5wt oil at 32 degrees, if it says 15w40 it flows like a 15wt at freezing.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top