LFA951

I have been changing mine every 3,000 miles/ 4 months, but I read here that changing it too often is actually bad, so how many miles or months is best for a street car daily driver?

Spidey944

I go 6 months or so, twice a year. But I have only put 4k on my car in the last year.

DanR

every 4 track days but I also drive to the track so about once per 1000 miles (400 track and 600 road). MOBIL 1

FRporscheman

street driven 968, 95% highway miles, I go 5k miles between changes.

LFA951

I think I'm going to go 5,000 miles in between too, since they are highway miles to work

Cory9584

I change the oil and filter every 3k with synthetic

reno808

every 2,000mi with 20/50 castrol even after the rebuild

Turbodan

why is it bad to change it too often?

DanR

there is a theory / thought that if you change the oil too frequently it does not have the opportunity to change its chemical structure due to use and it is this changing of structure which offers long term protection to the engine. Not seen any real data to prove or disprove this (but not saying it does not exist)

reno808

i was happy what i saw and so was jim. Thats good enough for me lol

333pg333

Sounds like Malarky to me. So this theory is suggesting that the protective qualities of your oil develops over time? Maybe a good bottle of Red, but not oil.
As for M1.........

FRporscheman

Not dissing you Dan, but that theory sounds like baloney to me. To me, long term protection means minimized wear during use, and minimized wear comes from optimized lubrication, and oil lubricates best when it's fresh and not ashy. I'm no oil guru though. The only reason I go until 5k is because I believe the oil is ok to that point, given the kind of use it gets with me at the wheel. Sometimes I do it at 4k.

DanR

no worries dissing me, to be honest it is NOT my theory or one I buy into! (as said, until someone out there puts some data forwards!)

dmalo810

Go to www.lnengineering.com and there is a good write up there on why not to change to frequently. Thru testing, not theory, they discovered that oil doesn't reach it peak until well after 3k that we've all been acustom to doing. Actually premature oil changes cause more wear in the engine. Also, they've done dyno and engine tear downs on nearly every oil out there and have established info on those oils that have the least wear capabilities.
In older engines, synthetics may not be your best choice.
They can also test your oil and tell you what is going on with the oil and your engine, how frequent you should change it.

When I bought my 951, the guy that owned it used Mobil 1 religiously. Also told me there was no oil leaks. Drove it a few times, got it home and started to notice spots of oil under the car. A friend told me about dumping syn and going dino and I didn't believe him. I then went to a seminar on oil by Charles from LN Engineering and Jay Raby (air cooled race engine builder). They explained the differences in formulas and calcium vs. ZDDP additives, blah, blah, blah. However, succes in their engines were from oils with more ZDDP and saw no wear advantages from syn oils. However, they did say in low HP motors they did discover that Amsoil was slightly better then Mobil 1 for HP gain.
So, I switched to a dino oil with more zddp and the engine runs more quiet and no more oil leaks.
Oils with more ZDDP are ASI rated SG, SH, of SJ. Oils rates SL/SM have none or a lot less zddp and more calcium. Motorcycle oils usually contain more ZDDP.
Another proponent of oils with more ZDDP is Lindsy Racing. I think they would know what they are talking about.

333pg333

It also depends on the detergent levels and what sort of temps the engine is seeing.
Those guys know what they're talking about for sure though. Unlike some other self professed 'Oil Experts' you see around on the boards.