Aries9

Since I have about 12 quarts of oil and I use mobile 1 I figure I can get away with not changing it very often. If the norm is every 3000 miles I can go 4 times that right? I'm at about 10,000 miles and I'm thinking about just changing the oil filter. I mean, mobile 1 is synthetic and doesnt really break down right? So what are your suggestions?

Thanks
Seth

r911

Change it every year no matter what mileage.

10k is not a problem. I might be nervous about going past 15,000.

paradisenb

I use mobil 1 and would not go over 6k no matter what. Oil change $60.00 Motor $15,000.00 DOH!Change every year regardless of milage? Absolutely!!!

Steve Weiner-Rennsport Systems

If I might offer,.........

the main reason for changing oil is not breakdown, almost all SG or better rated oils last a long time; rather its to flush the byproducts of combustion out of the engine that leaves carbon and sludge on the internal parts.

You would not believe the messes we see from infrequent and insufficient oil changes. Its cheaper to change oil than rebuild engines, even using $4/qt synthetics.

911Dave

Every 5k miles for me. And the newer the engine, the more often you should change it.

Zen dude

once a year, but use a synthetic filter also, like mobil 1 or K&N filter.

Steve Weiner-Rennsport Systems

With all due respect for Zen dude,....please do NOT use a domestic filter,....use the Factory Mahle ones.

I've seen my fair share of destroyed engines from various Yankee filters. Its due to either filter case failures and/or bypass failures.

The biggest offender is when the case splits away from the base and oil squirts out. You never see that until the damage is done.

pjc

Oil change is a big issue in the UK Porsche world at the moment - in particular with the Boxter where Porsche seem to be pushing out the change intervals. Talking to the oil companies they would suggest that their fully syn. products will go tens of thousands of miles without change, they are looking long term for a 'fill for life' solution believing that the product prevents any metal wear - however, like everyone else on this thread I'm old fashioned and believe that changing the oil and filter(s) frequently is a cheap option to retaining a robust engine. Both my 993 and my old '76 911 get a change every year - even with very low mileage. With older cars I believe it is essential.

I also believe in using Porsche supplied filters - the results of getting it wrong don't bare thinking about - my poor babies!!

PJC

Mark sP

I just checked my oil today. Mobil1. Its been in since mid November and covered about 6000 miles.

Level is AOK, and it still looks clean. Seriously, I have never seen oil looking so clean. The same oil in my quattro gets very dirty after 3000 miles.

I reckon I will leave the oil change untill 10k miles.

DonMo

Once a year oil change with synthetics (10-12k miles), change filter with Mahle every 3-5k, routinely get the oil up to respectable operating temps to make sure you boil off what you can.

r911

combustion byproducts are well-buffered by synthetics; also they need no or fewer VI imporvers (which are long spring like molecules that can coil up or stretch out to improve viscosity - these breakdown at high temps., creating gunk)

So, you can certainly go a lot longer with synthetics than with dino oils. Also, note the extreme engine longevity of 911s -- and that mostly involves using older oils from many years ago.

OTOH, there is the rel. cost/catastrophe issues noted above.

So, to me it really boils down to how paranoid are you.... or how prudent.

Doug Hillary

Hi,
I have done extensive new formulation oil tesing and used oil analysis (UOAs) over nearly 40 years in a wide variety of engines.

You may like to access the 928 Forum here and search under "Oil Condition....." report and you will find seven (UOAs) from my 928S4. The eigth will be posted in September and confirm Porsche's original oil change intervals with ease

This site may also be of some interest;

http://www.landsharkoz.com/techtips.htm

Check under "Lubricants for the 928"

Modern lubricants and especially the CI-4/SL synthetic "mixed fleet" Heavy Duty Engine Oils (HDEO's) are very durable indeed and offer engine protection (from corrosion,deposits,higher shear strength and etc) unheard of even 10 years ago. Such an oil is Mobil's Delvac 1 5w-40 - others are Shell Rotella T and a Delo variant from Chevron-Caltex.

Mobil's new M1 "SuperSyn" formulation in the correct viscosity is without a doubt the choice of most Tribologists as the most cost effective synthetic oil made today. A very advanced product indeed, it is a very different product from the old TriSynthetic formulation.
If using a "petrol" oil it should be ACEA's A3/B3 rated which will ensure that it meets the High Temperature High Shear (HTHS) viscosity minimum (at 150C) of 3.5cSt nominated by Porsche

An oil's anti-wear and other parts of its additive package (and its viscosity polymers) are temperature sensitive with their effective commencement at around 40C - depending on the oil. Generally, oil must get above 80C and operate around 88C-95C regularly to remain effective over long periods and the use of MANN or MAHLE oil filters is important because of their diffrential by-pass valveing and overall structure

Regards

paradisenb

F-n-A, Doug. You are either a chemist or pedantic. Great info! Thanks for the post. Now, how often do you change your oil and filter?

Forgive me Aries9, don't mean to highjick the thread, but had to dig into this a little deeper.

MRFLATSIX

My '70e gets used about 5000 miles a year so the oil is changed once a year. Absolutly German filters. I took the Woods/Anderson overhaul class a few years ago and both Jerry and Bruce were emphatic about the filter. An interesting side note, back in the '60s the Briggs oil filter became very popular among P owners. This used a molded clay block of diatomacious earth or "fullers earth" as the filter medium. The trick was to use #10 Kendall non- detergent oil. (that's right #10) the oil was never changed!!!!! the filter was changed about every 1200 miles. Engines that used this filter showed no wear after 100,000 mile tear-downs, The filter removed all carbon, varnish and sludge and left the oil like new. I rebuilt my '66 912 and installed a Briggs. After driving it for 35000 miles I sold the car which ran perfectly and showed no varnish at all in the valve covers. I was unable to use #10 because of consumption and availability and stuck with 30 weight. oil consumption was about 1500 miles to a quart. Before installing the Briggs I checked my valves every 3000 miles and 2 or 3 would need adusting. after the Briggs I drove it 35000 miles and it only required one adjustment even though I still checked it regularly.A couple of 904's on the west coast were using the Briggs in competition with good reults. (I'm not sure about the names so I won't mention them) One guy said he had considerably reduced cam lobe wear.The guy promoting these filters died in the late '60s and the whole idea died with him. I'm not sure how these filters would work today but at the time they were the hot tip.

Doug Hillary

Hi,
ParadiseNB - I am on annual changes (up to 20kkms) with my 928S4. My next annual change and Used Oil analysis result will be published on the 928 Forum as were the previous seven. My Z3 OCI is via the "service computer" and UOas but about 15 months and 20kkms. With my Outback the OCI is 20kkms but I do that in about 4 months or so

With my heavy trucks (OTR rigs with 500hp Detroit Diesel 12.7ltr DDEC4 engines) I have been changing oil at 100kkms (62k miles) for years and millions of kms and I recently carried out a tear down at 1m kms. The engine passed Detroit Diesel's and Mobils "reassemble again - no new parts required" inspection standards

Filters are changed only at the OCI. I have cut filters open for many years to find hardly any contamination - ever

I use Mobil's Delvac 1 5w-40 a CI-4/SL Heavy Duty Engine Oil in nearly all engines. Some have Shell Helix Ultra synthetic installed (to keep the oil suppliers honest)

The secret is to forget the hype about Brands and concentrate on the specifications needed

Regards