[tamathumper]

Believe it or not, even after everything I've done to this car, I've still never personally changed the oil, so now it's about time.



I've got six quarts of Mobil-1 15W50 and a K&N filter ready to go... Anybody want to talk me out of it? Be specific, e.g. conventional vs. synthetic, what brand and weight, etc. assuming driving in spring-to-fall NorthEast temperatures, road use only.

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[flash]

nothing wrong with that.



i prefer the higher temp capabilities of amsoil, but it's sure a lot harder to get ahold of.



i also prefer the canton oil filter, as it is a whole lot easier to change, and does a better filtering job, but it's a LOT more expensive.

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[tamathumper]

I thought the K&N was expensive enough, but the Canton is about 10 times that with shipping and tax!

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[earossi]

Sold my last 968 several years ago; but, thought that I would log on today and see who is still here. And, then I ran across this post inquiring about engine oil. So, I have something to offer to the forum. I have moved on to a 993, and suffered a lubrication related failure requiring replacement of a camshaft. In researching the failure, I began to run across an evolving story on engine oils that I need to pass on, if it has not be discussed on this forum.



In short, folks that own these older cars that have rocker arm actuated valves, should consider changing oil brands entirely. Here's the story.......in approximately 2006 (someone can post the actual time), the US EPA posted regulations that required that the catalytic converters in cars be able to function for 200,000 miles. I believe that the old regulation called for cats to have a life of 100,000 miles. Not sure why the EPA changed the regulation, but I have confirmed that it was changed. The relationship between catalyst life and oil is that the oil additive ZDDP (zinc/phosphorous) will render the platinum catalyst ineffective at about the 125,000 mile point. Apparently, the ZDDP coats out on the catalyst long term. So, oil specs were changed by API reducing the level of ZDDP in street motor oils. Historically, premium oils (Including Mobil 1). Had ZDDP levels of greater than 1300 ppm. The API spec cuts that level down to about half of the previous standard.



Unfortunately, the reduced levels of ZDDP are beginning to show up in camshaft failures such as the one that I experienced on my 993. I called around to some of the Porsche builders and confirmed that they are starting to now see an increasing number of lubrication related engine failures that are caused by the reduced ZDDP levels. This failure mechanism is only occuring in older cars with higher power motors. Newer cars, for fuel efficiency measures have gone to roller cams to lower internal mechanical friction.....but, our older cars have rocker arms that run against cam lobes.



So, what is the solution for us old car owners? Well, you should evaluate the use of off road or racing oils which were not affected by the API standards and still contain the proper ZDDP levels needed for our cars. Having researched this, I can point you to evaluating oils made by Joe Gibbs, Brad Penn, and Motul. If you want to stay with Mobil 1, the good news is that Mobil 1 for motorcycles still has the proper level of ZDDP.....at least until the EPA gets around to requiring cats on cycles!



Sorry for the long post; but, felt that the forum needed to know what I have found out......the hard way.

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[tamathumper]

Thanks for a very well written, considered response.



Forgive my mediocre understanding of engine terminology, but I know the 968 has what I'd call "lifters", while I don't believe it has what I'd call "rockers" - at least not in terms of how I understand the boxer (or old Fords and Chevys) work with an actual rocker and an arm?



After a little bit of reading, I believe Mobil 1 15W-50 still has about 1200-1300 ppm ZDDP, which is why I chose it.



The whole cat issue is another bag of apples, as they are getting few and far between and are NLA from what I understand?

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[bva]

+1 on the canton filter. Makes an oil change a much cleaner job as well.

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[JTP]

I've been running Millers 5W40 and very happy with it. car seems to run much smoother.

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[MB968]

Good info for us old car owners.

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[Chris Vais]

I've been running TOTAL Classic, a French product for some time now on the advice of my PM. It retains the higher level of ZDDP that our older engines require.

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[Kim]

I bought an additive, ZDDP Plus, from RS Barn and I have been using that on each oil change.

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[cosimo]

Motul, far and away the best. Pricey but well worth it.

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[DaveN]

Motul is what my PM uses exclusively.

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[Cloud9...68]

Thanks for the informative post, but it reminds me of a Far Side cartoon I saw years ago, in which a family of fish narrowly escapes a fire in their bowl, only to realize, as they're standing on the table next to their flaming home, "'Course now we're equally screwed." So the high levels of ZDDP will prolong the life of our cam lobes and lifter surfaces, but ruin our NLA catalytic converters. What's a hapless 968 owner to do...?



Edit: It just occurred to me that a cat failure due to the high ZDDP oil (Joe Gibbs) I plan to use may be a major deciding factor in when I take the plunge and turn my car into a full-blown track car...

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[flash]

that's exactly what makes me leary of the additive route. those things never mix quite right, and i'm concerned that it will ultimately burn in the chamber and consequently ruin the cat.

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[Cloud9...68]

[quote name='flash' timestamp='1363793054' post='140336']

that's exactly what makes me leary of the additive route. those things never mix quite right, and i'm concerned that it will ultimately burn in the chamber and consequently ruin the cat.

[/quote]

When you say additive, do you mean an oil with the additive blended in it, or are you referring to the use of a stand-alone additive you add to the oil?

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[cosimo]

Check out the Motul web site. IMA uses Motul exclusively. It;s lesson learned from L&N enginnering that supplies IMS faiure solutions for Boxstersand 996s. I have used in my car for at least 2 years. I used to use about a quart every 600 to 700 miles and now it's well over 1000.

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[Chris Vais]

I go about 1200 miles on a quart and that includes the loss from a leaking pan gasket.

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[JTP]

Although I use Millers now in my 968, I used Motul in my Boxster. Great oil, I also only use Motul in my motorcycles.

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[Lear35A]

As suggested, I went on the Motul website. Looks like they make MANY different blends and weights of automotive oil. Which particular one are you guys using?

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[tamathumper]

The only two I found with Porsche approvals were the 8100 series in 5W40.



http://www.motul.com/us/en-us/fluidsearc...5D=porsche

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