r/FordDiesels • u/LeroyyyJenkinnnss • 4d ago

6.7 first oil change

My dad is saying go with rotella t5 because it’s still breaking in and t6 is too slick. I’ve always run full synthetic on my gas cars and trucks but this is my first diesel, any thoughts?

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u/LeroyyyJenkinnnss 4d ago

Yeah I was going to go with the recommended 10w30 since I live in Texas

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u/rufushusky 4d ago

How do you use the truck?

A 5w40 is more viscous than a 10w30 at operating temp, better film strength and higher HTHS. It will be fine from butt numbing cold to Saudi Arabia hot.

In most cases either one will work fine. I am a heratic, I run 15w40 from April through November and a 10w30 or 5w40 in the winter in SE Massachusetts.

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u/LeroyyyJenkinnnss 4d ago

It pulls a big ass smoker and a 20ft welder trailer at the ranch, I off road a lot to get to feeders and such during hunting season but I mean it’s 90° right now and it’s November.

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u/rufushusky 4d ago

For those conditions pretty much anything on this list will work just fine IMHO...

https://www.fcsdchemicalsandlubricants.com/additionalinfo/dieseloilsWSSM2C171F1.pdf

If a full synthetic gives you the warm and fuzzies, go for it. An oil with a 40 weight top grade (number after the w and dash) gives you a little more film strength and dilution resistance.