Synthetic oil- Oil change intervals

[Dually]

I'm switching to Castrol Syntec from Castrol GTX and going from 3K to 5K mile oil change intervals.My hope is to have a clean internal engine like other people have had using Redline motor oil.What are average oil change intervals using synthetic oil without the oil being tested?I do mostly highway/very little stop and go.Thanks Joe

 

[AndyH]

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I'm switching to Castrol Syntec from Castrol GTX and going from 3K to 5K mile oil change intervals.My hope is to have a clean internal engine like other people have had using Redline motor oil.

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Not sure that Castrol Syntec will keep your engine as clean as Redline. I believe the Redline cleanliness comes from it's Ester basestock...Castrol Syntec (except for GC) is a Group III.

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What are average oil change intervals using synthetic oil without the oil being tested?I do mostly highway/very little stop and go.

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I'd say somewhere between 5,000 and 7,500 miles.

 

[ConfederateTyrant]

A lot of the used oil analysis performed here tend to be around 5,000-7,500 miles for synthetics. With that said, if you are not looking to analyze the oil for long drains, then 5,000 miles would be a breeze. I do not doubt that you could go 7,500 miles though, but would suggest a used oil analysis for the first couple of intervals at that length.

 

[GMZ]

Syntec (Even the GIII stuff) is good for 5K at the very least. Anything less would be a waste. I used to run that oil in my 350Z for 7.5K and got stellar results with no consumption. Heres the used oil analysis if youd like to see yourself, the car was driven very very hard also. Keep in mind that each car is different not only in wear rates, but its effect on an oil. Id agree with doing a used oil analysis or two at your desired OCI to make sure things are going smoothly.

 

[vronline]

Depends obviously on the vehicle and how you drive, but I run mine 10,000.

 

[Patman]

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Not sure that Castrol Syntec will keep your engine as clean as Redline. I believe the Redline cleanliness comes from it's Ester basestock...Castrol Syntec (except for GC) is a Group III.

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Syntec's base oil isn't entirely group 3 though, it does have some esters in there too (and possibly a bit of PAO too) But it won't have nearly as much esters as Redline.

5k intervals with Syntec should give you a clean engine though. I think 5k is a bit too conservative, you should do a used oil analysis to see how much further you could go. I'm sure you could go 6-7k (or more) without a problem.

 

[Ron AKA]

You have the intervals right. Just change it and don't bother with used oil analysis. There is no Redline standard to worry about. They don't even meet basic API standards.