Synthetic oil-How many Miles?

[recneps]

I just changed the oil in my 1999 4.0 and was wondering how long I can go on the castrol 5w-30 fully synthetic. Anybody know?

 

[hoosier1104]

5K is normal for most synthetics. I am running AMSOIL and it is good for 25K or 1 yr, which ever comes first.

 

[adsm08]

I'd say 5K.

 

[nitrofan1]

If the engine is in good shape etc....7,500 is what I go normally.

 

[JohnnyO]

Should be good for 7500. I would go 5000 the first time and send a sample to Blackstone Labs. If they say it's good, then go 7500 after that if you want. Although if I was going to run it that long I would use a Mobil 1 or K&N oil filter instead of Motorcraft.

www.blackstone-labs.com

 

[mentalbreakdown00]

not going to try to get into it, but castrol syntec is not actually a true synthetic. It cannot be labeled as such but in America.

 

[exbass94]

not going to try to get into it, but castrol syntec is not actually a true synthetic. It cannot be labeled as such but in America.

The same is true for most of the other off-the-shelf oils, such as Valvoline, Pennzoil, Quaker State, any store-brand, etc.

Edit: Oh yeah, regarding the original question: Start off at 5k and send it in for a used oil analysis. That is the ONLY way to really know for sure how long you can go between oil changes.

 

[mentalbreakdown00]

My last car my 2.3 4 banger stang 1993 I used amsoil 0-30 kept sampling until 15 K was the point where the oil wasn't quite depleted but getting close. In my 81 F-100 I got 1K, takes 6 months or so to do that, and in the terdyota I go 4K cause I don't wanna add any oil...

 

[exbass94]

I don't see how you fella's are changing your oil 5,000 and more miles. Whether full syn or not. I have used Ford 5-30 and Ford filters for years and always change it at 3,500.

Then you're still living in the 1970s. Changing oil every 3500 miles is WAAAAY excessive, wasteful, and pointless. Sure back then, you had to change it every 3k. But oils today are leaps and bounds better than oils made 10, 20, 30 years ago. Even the cheapest conventional oil can go 5k no problem.

 

[RangerSVT]

I run Castrol Syntec 10w40 in my truck, and worked near a truck stop that has an oil analysis machine, had it analysed at 5K, 7.5K, and at 10K, and said the oil still had its viscosity at 10K, so I left it at 10K and thats what I change it as....but keep in mind I was putting 600-700 miles a week on mine
SVT

 

[R***A**N**G**E***R]

5K is normal for most synthetics. I am running AMSOIL and it is good for 25K or 1 yr, which ever comes first.

25,000 miles in between oil changes??????????????????????? shit!!! Good luck with that.

 

[NMB2]

25,000 miles in between oil changes??????????????????????? shit!!! Good luck with that.

i do 20,000 between mine. I usually dont hit the 25k before a year. Right now my DD is at 11,000 since the last oil change.

 

[Hawker]

What's wrong with what the factory specifies? Don't know that I'd trust unknown responders over the internet more than OEM.

 

[Downey]

^^^ factor specs arent for full synthetic oil. Mobel one is a full synthetic right?

 

[Kona]

Well post your oil analysis sheets then 1st was Mobil 1 10w30 syn 2nd Castrol Syntec 10w30

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