Got a question. I run a kdd stage 1 long block in my 06. I’ve ran nothing but schaeffers 15w40 since it’s been broken in. I’ve been wondering if anyone runs a 5w40 or 10w30 in this particular engine? Kdd recommends schaeffers 15w40, but is there a particular reason for it? I know several people that swear by the 10w30 or 5w40. I tow heavy and summer weather is consistently over 100f. Winter isn’t bad. We occasionally get down in the teens. No issues starting or stiction in my case.
6.0 oil questions
- Thread starter Diesel625
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I can’t provide a reason for why they want 15/40 oil. Give them a call and have them explain their reasoning for that particular weight oil. I run Schaeffers OTR 5-40 in both of my trucks. With the HPOP system it’s gonna shear that 40 down to 30 really quick. That maybe the reason some run the 10-30. I’m sure someone else will chime in with better answers for you.
Getting back in the truck now.
Getting back in the truck now.
5W40 oil doesn't actually shear to a 30 weight all that quick. It will take around 5000 miles for some oils, and others can go to almost 7500 miles. I have taken a lot of data on this with various oils. Schaeffer 5W40 shears the slowest that I have seen, but it elevated the lead number in my UOA.
There isn't a huge issue shearing to the high range of a 30 weight at those mileages anyway, and choosing a 30 wt oil to run only because a 5W40 shears to a 30 weight isn't really logical.
In the 6.0L, Ford has always recommended a 40 weight when towing heavy (15W40 and 5W40 are BOTH recommended), AND also both are recommended for hot climates.
Sure a 15W40 will shear more slowly than a 5W40 because it has less VII additives. So that might be why they recommend it. That said, injector folks typically recommend a 5W40 over a 15W40 because it is less susceptible to stiction in cold climates. For this reason, Ford does not recommend a 15W oil below 20 degrees F.
BTW - all multiviscosity oils will shear - even 10W30 shears.
Rotella 10W30 starts out at 12.0 cSt. Several threads show it shearing to 10.57 cSt at 5k miles and 9.7 at 8k miles.
Mobil 1 TDT 5W40 and Mobil Delvac 1 ESP 5W40 starts out around 14 and in my truck and shear to around 12.1 to 12.4 at 5k miles. (right about the viscosity number that Rotella T5 10W30 starts at).
Schaeffer 9000 was around 12.7 - 13 at 5k miles.
SAE 30 weight viscosity range - 9.3 to 12.49 cStokes (100*C)
SAE 40 weight viscosity range - 12.5 to 16.29 cStokes (100*C)
HTHS viscosity might be a bit higher for a 15W40 oil than a 5W40 oil, but that would depend on the specific oil. Also, it isn't particularly clear if a higher HTHS is actually going to protect the engine better to any appreciable degree.
There isn't a huge issue shearing to the high range of a 30 weight at those mileages anyway, and choosing a 30 wt oil to run only because a 5W40 shears to a 30 weight isn't really logical.
In the 6.0L, Ford has always recommended a 40 weight when towing heavy (15W40 and 5W40 are BOTH recommended), AND also both are recommended for hot climates.
Sure a 15W40 will shear more slowly than a 5W40 because it has less VII additives. So that might be why they recommend it. That said, injector folks typically recommend a 5W40 over a 15W40 because it is less susceptible to stiction in cold climates. For this reason, Ford does not recommend a 15W oil below 20 degrees F.
BTW - all multiviscosity oils will shear - even 10W30 shears.
Rotella 10W30 starts out at 12.0 cSt. Several threads show it shearing to 10.57 cSt at 5k miles and 9.7 at 8k miles.
Mobil 1 TDT 5W40 and Mobil Delvac 1 ESP 5W40 starts out around 14 and in my truck and shear to around 12.1 to 12.4 at 5k miles. (right about the viscosity number that Rotella T5 10W30 starts at).
Schaeffer 9000 was around 12.7 - 13 at 5k miles.
SAE 30 weight viscosity range - 9.3 to 12.49 cStokes (100*C)
SAE 40 weight viscosity range - 12.5 to 16.29 cStokes (100*C)
HTHS viscosity might be a bit higher for a 15W40 oil than a 5W40 oil, but that would depend on the specific oil. Also, it isn't particularly clear if a higher HTHS is actually going to protect the engine better to any appreciable degree.
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I use to obsess about oil and lose sleepover it. More so used to think powerstroke killed oil. They do not. These engines are sparkling clean inside compared to common rail counterparts.
M1 TDT 5w40 goes about 10k miles in my 7.3. Blackstone says the additive package can go even further.
I run it in my iroc with a LS engine that's gets best to piss in the summer. I go about 5k since that motor sees 7k rpm on the reg. It tests fine.
Pick a good oil, send it to be tested 1 time to dial in what interval you feel safe at, and worry about other things.
I've been running Amazon oil in the SHO and Highlander. They always say take the oil to 7-10k miles. No issues.
M1 TDT 5w40 goes about 10k miles in my 7.3. Blackstone says the additive package can go even further.
I run it in my iroc with a LS engine that's gets best to piss in the summer. I go about 5k since that motor sees 7k rpm on the reg. It tests fine.
Pick a good oil, send it to be tested 1 time to dial in what interval you feel safe at, and worry about other things.
I've been running Amazon oil in the SHO and Highlander. They always say take the oil to 7-10k miles. No issues.
I know a lot of people would worry less about oil in the 6.0L if they didn't occasionally trash lifters.
On the other hand, I don't think lifter failure can exactly be attributed to an oil grade choice! My bet is that elevated temperatures play a role.
On the other hand, I don't think lifter failure can exactly be attributed to an oil grade choice! My bet is that elevated temperatures play a role.
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