How Many Miles Before Changing Synthetic?

[Titleist16]

I just switched over to synthetic oil yesterday and was wondering how many miles I can go between oil changes. I usually change my oil every 2500 miles but I heard synthetic can go for longer. I put in 10W-30 Mobile 1 full synthetic oil and a K&N Gold oil filter. I want to have this motor last for a very long time so what is the best mileage to change it at?

 

[Guest]

This is an interesting read:

http://www.newenglandclassics.org/Artic ... %20Oil.pdf

 

[Junk-Falcon]

i run

 

[Anonymous]

I figure you can't go to extreme oil change intervals in the old cars, because there are a lot more contaminants that find there way into the oil on the older cars as compared to newer cars. Newer cars have tighter clearances, fuel injection, better PCV and temperature control. Our old cars have carbs, looser clearances and often open - breathers that let air and unburned fuel in the crankcases. That is why you will see the oil in old carbureted cars get dirty faster than newer cars. So, I would limit the oil change interval to about 5K.
Al's article echoes many of the concerns and recommendations I have been seeing on the Corvett web sites too about the latest oil formulations. The concern started many years ago in air cooled motorcycles before it really hit the classic car world. Look for API oils with a CI or CH designation as theses stand for "Compression" diesel service. Oils with S such as the latest SM oil is for "Spark", 4 stroke spark ignition engines.
Doug

 

[CobraSix]

In my 200, I still use convential and change every 5k miles. 3k IMO is just too often and most research I've found is there is VERY little difference in oil breakdown between 3k and 5k miles.

On my Volvo, I went with manufacturers guildlines of 5k with either synthetic of conventional. I figure if Volvo says 5K miles, it must be good. That is the interval for turbocharged versions. NA Volvos are recommended at 10k with conventional oil. I'm running 0w40 synthetic in my volvo. 150k and still on the original Turbo...

On my 99 mustang, every 5k miles on synthetic. Easier to remember.

Slade

 

[mustang6]

In my 200, I still use convential and change every 5k miles. 3k IMO is just too often and most research I've found is there is VERY little difference in oil breakdown between 3k and 5k miles.

I am glad to hear a voice of sanity on this subject. Years ago I read a Consumer Reports test where they tore down the engines in New York taxis that went over 100,000 miles on different oil change intervals. They found no differences in wear until you got over 7,500 miles between changes, (and these were cars that did mostly stop and go city driving) even then only a small amount between the 7,500 and 10,000 mile interval cars. Over 10,000 miles there were increasing effects.

I remember when all the oil change chains used to recommend 5,000 mile oil changes. Over the years it dropped to 4,000. Oil has gotten better, engines have gotten tighter and run cleaner, fuel has gotten cleaner, and what has happened? Oil change chains now try and make everyone feel guilty if they go past 3,000 miles. It's a money making scam in my opinion.

 

[addo]

Hear, hear. Plus, if you're putting in an oil that's ostensibly "better" then you'd normally expect improved lubricant life!

 

[weeds]

FWIW - I use mobile 1 in my 97 GMC truck and change it avery 15k. It has 178k on it and no signs of problems.

 

[CobraSix]

The other thing is Amsoil actually recommends 25k mile changes on their synthetic.

5k miles just works out great for me. Easy to remember and I rotate my tires at the same time.

Slade

 

[blueroo]

My owner's manual for the Fairlane says you should change the oil every 6000 miles...but you need to use the Rotunda Gold 6000 Mile Oil Filter aka the oil filter that made the 6000 mile interval possible. Yea, Ford definitely made that an infomercial in the manual.

I think one of the reasons the interval had dropped is because the heat motors are making has increased from 160 to what is now 210-240.

I really like my Royal Purple. I've only had to add a small drop of it at around 1300 miles after the change. It starts a lot smoother too.