Paulyy

Service time..
Penrite (the oil i usually use) have changed their product line again..

Is there a recommended amount of ppm of zinc we need?

333pg333

Probably somewhere between 1000 & 1500ppm. As an approx guide. What are Penrite saying?

Paulyy

1600 on the HPR series which is the one i've been using.
2200 on the 10tenths racing series.

I need to check, but last time i used 20w 60 (HPR30) and was synthetic and now it's mineral oil. and the 15w 60 (HPR15) is synthetic.

I broke the car in on mineral oil. then ran semi synthetic as that's what they had at the time. then they changed to synthetic and now its back to mineral??

JET951

Its not as easy as that because you could for Australian ambient temp conditions use the wrong oil viscosity but the correct ZDDP , and you will damage No 2 conrod bearing ( big end bearing )with normal hot oil temp, meaning oil / core temp at high RPM / high load , this is made worse by higher than normal boost , meaning there is much greater load on the conrod bearings in these conditions .

944 ( all ) suffer from oil bubbles forming at high RPM ( naturally hot oil ) & these air bubbles always head for no 2 conrod bearing & at the track = BANG , even on the street we have seen them let go , particularly on a 5w-50 viscosity ( it just speeds up the destruction )

How do we reduce / eliminate this potential damage to these last century engines ?

Answer = We consult the owners manual that came with these last century cars & it states }
From Minus 10 deg cel to Unlimited high ambient temp use 20w-50 or 15w-50 oil viscosity engine oil

But why is it so ?

Answer = Oil Film Strength & proper oil pressure at these critical conrod ( big end ) bearings

But how ?

Answer on oil film strength = There are only two commercially available ways of increasing oil film strength in engine oils sold to the public

A ) Increase oil viscosity from say 5W-40 to say a 20w-50 , with both these engine oils with the same levels of ZDDP , which is almost not going to happen because the street ( non race ) 5w-40 engine oils are nearly always lower in ZDDP ( for this century cars ) as opposed to a last century oil viscosity like 20w-50 which are nearly always have higher "Read" decent levels of ZDDP , because 20w-50 engine oils are a predominant last century engine oils for last century cars and last century engines ( particularly these early 1970's designed 944 high loaded flat tappet designed 944 & 928 engines ) that were designed around the new kid on the block ( in the early 1970's ) in regards to engine oils & that new kid was the 20w-50 oil viscosity as compared to the 1960's straight mono oil grade oils like SAE 40 and the like & last century cars were permitted to have much higher levels of ZDDP ( hence why 20w-50 is nearly always a safe choice

NOTE } I do not always trust some 15w-50 engine oils sold to the public , because there is much more of an overlap in early this century cars that could use 15w-50 & oil companies are happy to reduce the ZDDP in these to sell to a wider customer base & yes there was one classic case 15 or so years ago when a large oil company here in Aus decided to lower the ZDDP on their 15w-50 & within a relative short period of time cam wear etc went through the roof & within a period of time the oil company put the ZDDP levels back , What A Joke that was , but no one laughed

Naturally if you lower the ZDDP on a engine oil for emission reasons ( read this century street oils ) you decrease its oil film strength

B ) 944 8 valve & 16V engines ( like the 928 series ) are bordering on extreme High Loaded Flat Tappet design engines , meaning Cam Lobe wear is assured if the two oil film strength formulas are not met
Meaning as higher oil viscosity as possible as per the ambient temp + Good levels of ZDDP

Hence why we see so much cam wear on last century Porsche engines with a too lower viscosity & this is nearly always goes hand in hand with lower levels of ZDDP =

Excessive cam lobe wear & hydraulic lifter face wear
Excessive valve guide wear
Excessive cam chain sprocket wear ( twin cam engines ) = 944S , 944S2 , 968 , 928S4 etc etc
Excessive crank Thrust Bearing wear
Excessive Piston to cylinder wear ( mainly turbo / 951 engines on higher boost )
Air cooled 911 valve guides , rocker shafts to cams, rocker shafts / bearings, ,timing chains/ sprockets, pistons to cylinders

Have you noticed all the worn out items mentioned above are all mechanical parts that get NO OIL pressure at all , they just get oil splash, which means they rely on Oil Film Strength ONLY & you must have the two ingredients to make this happen ( high oil Viscosity + Decent levels of ZDDP )

If the Oil Film Strength is lowered = accelerated wear or worse

Do we see the above components are run on a 20w-50 with decent ( not excessive ) ZDDP here in Australia , even at 400,000 Kms & the oil is changed every 10,000Kms for NA and 5,000 Kms for Turbo ?

Answer = NO

I have been working on Porsche's for 38 or so years & this is what we see ( Every Day )

PS } we are the only ones at the track over the years that have no issues at all ( even Pats monster engine does not have conrod / journal destruction, Sean's 1986 951 won the 2014 PCNSW Drivers Championship ( not the first time ) & won the Motorkhana Championship ( again ) & Sean's custom 16V 3.0L E85 600+ HP monster still has a standard wet sump & NO extra baffles or the such , just excellent oil temp control + good crankcase ventilation + a engine oil that is a Min Viscosity of 25w60 & being a competition oil its quite high in ZDDP & lower in detergents to prevent foaming & MUST be changed after every event or every 3 months & I mean MIN Viscosity of 25w-60 ( read into that what you will )

NOTE 2 } Have you ever wondered why on earth do we still rely on the last century ( Read WWII ) oil AW additive = ZDDP ????????????
Think of the millions & millions of dollars & Decades of time spent on research & making of so called fully synthetic engine oils , but these poor oils still NEED ZDDP to keep metal parts away from each other ( What sort of Joke is this )
With all the hype in advertising I thought that the last thing a this century latest & greatest so called fully synthetic engine oil would ever use is a 75 year old oil additive( Yes 75 years old ) that they do not want to use , because the emission protocols dictate its removal or at best a massive reduction , I thought the fact that it / they are so called synthetic would be enough , but its not the case at all

You only have to research Racing engine oils ( these are Exempt from the emission protocols ) and oil companies are falling over them selves saying how much ZDDP their racing fully synthetic engine oil has

Paulyy

Awesome write up!

But do you use synthetic with additives (penrite HPR15 15w 60) ppm not stated.
OR
mineral oil (penrite HPR30 20w 60) 1600 ppm zinc

They've changed from last year.

I'm leaning towards HPR30 which is usually what i get.

JET951

Sean runs Valvoline Racing 25w-60 all year round ( multiple oil changes per year ), for our road customers we only use 20w-50 Valvoline Maxlife

If I was to use Penrite I would go for the 20w-60

Cyberpunky

Sean/Bruce
I have started using Pentrite 15W-50 Racing 15 10tenths oil. Should I use there 20W-60 Racing 20 instead ?
I notice you havent mentioned what you use. I trust your expertise on these cars and would love to know what you use on your personal cars. PM me please if not wanting to post info publicly
cheers
Bruce

Cyberpunky

Wow you answered my queston while I was still typing it lol

gruhsy

The above post on oil from JET951 should be the opening page for the 944 forum page Awesome!

Paulyy

10tenths isn't worth it on the streets. you'll never see the full potential.

67King

Caveat emptor!!!!!

To quantify an answer for the OP, the upper limit you really want to see is about 1300. Many of the, let's just say marketing focused (rather than engineering focused) race oils out there will put way more than needed in them. How much more? One extreme example is nearly twice as much.

So why is this bad? Two reasons. First, for the better race oils that use some amount of ester base stock (range is usually 10-20%, most falling in the 10-15% range), ZDDP and ester are both polar, meaning they fight each other for surface area. They protect in different ways. If you have too much ZDDP, then the ester won't be able to get to the metal surfaces. Second is a little more simple. ZDDP is a thick, gooey, honey like substance. It is great at protecting, but causes drag. The more ZDDP you put in the oil, the more drag it creates. That increases friction.

Here is a link to a chart that shows the result of this. This oil has tons of ester, but also tons of ZDDP. It is a well known brand, but I also heard more grumblings at PRI this year about people losing engines from running this oil. Nevertheless, the blue line is the coefficient of friction, and the green line is oil film. Bad oil. A good oil should have notably higher oil film thickness, at least 60%, closer to 100% is better, and lower coefficient of friction (about 50% less is where some of the better oils are).

On the viscosity, there are a few things I'd like to mention. What is probably the most important viscosity number is not listed by SAE, which is frustrating. It is HTHS, or High Temperature High Shear viscosity. That number may be higher with a "thinner" oil. For example, a well known 0w50's HTHS value is 3.8cP. So one would expect a 5w40 to be thinner, right? Well, the Millers 5w40 is 4.4cP. So the 5w40 is going to be thinner than a competitor''s 0w50. FWIW, I'll be running the 5w40 in my 968, but keep the Turbo at 10w50, strictly for the issue of fuel dilution. Note this is for race oils.

On 15w50's. Those are almost always a synthetic. And newer oils are better, which gives you a higher viscosity index (the relationship between cold and hot viscosity - a 15w50 will have a higher VI than a 20w50).

If you are driving on the street and not the track, many race oils are overkill. Not sure what is available in what parts of the world, but in the US, we offer some Classic stuff from Millers, which is geared towards street use, but contains proper levels of ZDDP (about 1250). What I've had a few 951 owners buy is Classic High Performance 15w50, which is a fully synthetic street oil for that period of cars. It is unfortunately being phased out (we still have lots in stock to hedge against that), but is being replaced by a Classic High Performance 20w50 NT - it uses the nanotechnology that the race oils do, and is a 20w50, frankly because the market is so accustomed to a 20w50 that Millers was basically forced to make it that, rather than a 15w50, in order to sell it. I'd recommend the 15w50, and it is notably less expensive.

One thing you can do is look for something like an SJ or SL oil or something, but not newer. The SM knocked the ZDDP back to no more than 600 for the thinner oils, but not for the thicker ones......but most didn't use them anyway, and there was a second "energy conserving" binning that isn't really widely advertised.

I'll try to check back on this and see if more questions pop up, but I do have to be careful, as I dno't want to get too close to "advertising" since we're not a site sponsor right now (we have been, but those are typically set up for marque specific vendors, rather than product specific vendors).

Thom

Great input, thanks Bruce and Harry.

Any opinion on the Millers CFS 10W50 NT?

blade7

I've been using Millers 10w50 CFS for around 5 years, I wait until my supplier has a offer on and buy then, but it's getting more expensive and apparently Millers now tell their dealers not to discount their products, so I am looking around for a comparable alternative.

jasonlp

Any input on Liqui Moly Race Tech GT1 oil - 10W-60 ?

KSira

Used Miller 10-60 NT for this years season, so far no issues, except for the damage to the wallet. This is oils expensive in Scandinavia.