What time/mileage for oil changes?

[HERCULES-550]

How often should I change my oil? I dont run my truck as much as I used to. I usually change the oil every 3000-3500 miles. Is that ok? Is that too often? It is getting very expensive now that oil is $13 a gallon. Will the oil go farther that that. I also use a gallon of synthetic when I do an oil change. I use 10 qts of Rotella 5-40 and 4 qts of Rotella synthetic.

Also how often should you change your gear oil and what kind is a good recomendation?

[tfifeco]

What truck do you have? I have the 250 7.3l and change mine every 5k miles. But mine is my daily driver. Also, i didnt think you could/should mix synthetic with regular oil. you said you dont drive it a lot, how long does it take you to get to 3500 miles?

[rufushusky]

Originally Posted by HERCULES-550

How often should I change my oil? I dont run my truck as much as I used to. I usually change the oil every 3000-3500 miles. Is that ok? Is that too often? It is getting very expensive now that oil is $13 a gallon. Will the oil go farther that that. I also use a gallon of synthetic when I do an oil change. I use 10 qts of Rotella 5-40 and 4 qts of Rotella synthetic.

Also how often should you change your gear oil and what kind is a good recomendation?

The factory OCIs on a 7.3 PSD is 3000 miles severe duty, 5000 miles regular. The T444e (an engine that the 7.3 PSD is based on) recommends 8k/10k service intervals. A 5k run on even the cheapest fleet grade oil is fine IMHO, CJ-4 oils are light years ahead of CH-4 oils (the standard grade in the late 90s -early 2000s). Check out bob is the oil guy, you see a lot of boring (in a good way) UOAs from 7.3s running all sorts of OCIs.

With respect to gear oil, the front pumpkin specs 75w-90 (doesn't mention whether or not it should be synthetic or not) and per the user manual the front axle doesn't say touch the fluid until 150k. IIRC the rear end on the dually specs a ton of 75w-90 but I will leave that to the dually people.

For gear oil, a synthetic is never a bad idea....I think under the special operating conditions the manual recommends 50k intervals...which when I change mine out just to be safe.

[Mark_be]

Don't mix synthetic with regular! Found on google:

Synthetic and conventional will not "mix" and synthetic creates a barrier on moving parts, that conventional cannot pass. So, too much synthetic, as in a 50/50 blend, will be like running an 8 quart system on 4 quarts, without starving the oil pump. It will break the synthetic oil down quicker...

Read more: Is it harmful to mix regular motor oil with synthetic

[rufushusky]

Originally Posted by Mark_be

Don't mix synthetic with regular! Found on google:



Read more: Is it harmful to mix regular motor oil with synthetic

Well you found it on the internet...it has to be true right?

IMHO that is answer is pure and total garbage....forming some barrier? That conventional oil can't penetrate? Are the Spartans in your motor oil? Motor oil's most basic job, regardless of base stock, is form a protective barrier on moving parts.

Secondly, I am sure whoever wrote that post's head would be blown to find out that group three synthetic (eg. Rotella T6, Valvoline Premium Blue Extreme etc etc) are actually at least partially hydrocracked dino base stocks ... so claiming that synthetics and conventional won't mix cause of the base stocks is effectively claiming that dino oil and dino oil can't mix. That makes a lot of sense.

Even in the case of PAO or ester based oil (group 4 and 5 base stocks) you can mix the base stocks to any ratio without issue.

AMSOIL Premium API CJ-4 Synthetic 5W-40 Diesel Oil (DEO)
Valvoline.com > FAQs > Motor Oil Car FAQs > Full-Synthetic Motor Oil
Synthetic Oils FAQs
http://www.castrol.com/castrol/gener...tentId=7017050


You could go on and on...personally I believe the people that actually make the oil over some guy on wiki-answers or whatever the site is...

[HERCULES-550]

Thanks for all the info. I was hoping that I could push the oil changes to 5k. It gets a little expensive changing the oil all the time. I was doing 15k a year but at times more than that. This last year the truck has been down so the mileage is lower. I have been mixing in the synthetic for a long time on all my vehicles and never had a problem.

On most of the engine issues does it matter what truck it is in? I thought all the 7.3 TD were all the same? This is my first diesel and have only had it for 6 years so I am not very knowledable about these motors. I learn something new every day.

Thanks again

[alradco]

I go about 5k miles