View single post by Esprit2
 Posted: 06-21-2017 08:21 pm
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Joined: 05-01-2005
Location: Minneapolis, Minnesota USA
Posts: 338
scottsmi wrote:
On the subject of oil, I read your previous post on the viscosity and wonder what your opinion is of using zddp. I have found break in oils with it but not much else at my local autoparts store.All modern motor oils contain ZDDP, some more than others. The problem for vintage car guys is that beginning with API SL, the ZDDP was severely reduced. Our engines depend upon ZDDP, and much of it was taken away. Vintage flat-tappet cams are especially vulnerable to damage when running modern low ZDDP oils.

IMHO, using a ZDDP additive is a distant second best. ZDDP doesn't work alone, and other elements must be present in order for it to function. Also, many modern oils are replacing the old sodium based detergents with calcium based detergents. That's a problem since the calcium versions are (for lack of a better term) 'abrasive' in their own way. For the same level of anti-wear protection, those oils with calcium based detergents require more ZDDP than oils with sodium based detergents.

Getting to the point... motor oil is a complex soup. And simply pouring in a jug of ZDDP additive doesn't guarantee you'll end up with the correct balance of elements your engine needs. It's a far better option to start with a properly blended motor oil that is right for your engine in the first place, and not trying to use an additive to make a silk purse out of a sows ear.

I spend my first four years out of college as a Lubrication Engineer for Texaco, so I have a little bit of a foundation for my opinions. And they are just 'opinions'.

The first opinion that gives focus to my choice of oils for vintage engines, is that 1200 ppm is the minimum level of phosphorus I'll use in my vintage flat-tappet cam engines... Lotus 9XX in particular. Not ZDDP, but phosphorus, for which ZDDP is the common source. It's commonly called "Zinc" only because "Z" is the first letter in the acronym, but it's the PHOSPHORUS that's important to your engine.

ZDDP is a complex molecule with Zinc & Phosphorus. In water, you get two atoms of hydrogen for each atom of oxygen. In 'X' amount of ZDDP, there's more zinc, and less of what you want, phosphorus. In round numbers, the balance is such that 1200ppm of phosphorus will bring along approx 1300ppm zinc. When an oil company says 1200 ppm, is that ZDDP, zinc, or phosphorus? If they don't clearly state which, then the default is ZDDP, in which case you're getting something less than that in phosphorus.

My second personal opinion is specific to Lotus 9XX 4-cylinder engines (JH 907), and that is that the oil should be of __W50 viscosity or heavier. That's less of an opinion, and more of a Lotus Engineering design choice that's not up for debate. The low temperature __W part can vary all over the map, but the high temperature part should be 50 or above. That's a matter of main and rod bearing design, and not a function of owner opinion. Every early Lotus engine, prior to the current Toyota powered Elise/ Exige/ Evora, was designed with large bearing clearances that depend upon 1) a heavy weight oil, 2) high oil flow rate, and 3) moderate oil pressure. That design decision has been made for you, and personal opinion isn't a factor.

If you're modern Honda uses 0W30, great for it. It was designed with very tight bearing clearances, and depends upon high oil pressure and moderate oil flow rate... the opposite of a Lotus 9XX. The fact that your modern car works well with a thin oil doesn't mean thin oil is good for your 907. It's NOT ! -- Sorry about the rant.

I don’t pretend to know all the “street” oils that provide elevated ZDDP levels, but some are more easily found on the internet. The chart below gives some numbers on oils out there that, IMHO, are safe for use in vintage engines. I use Mobil 1, but I have no connection with Exxon Mobil and I’m not pushing Mobil 1. You choose yours. Of the Mobil 1 synthetic oils, I prefer 20W50, but I also use their 0W50 Racing Oil, and in a pinch, their current 15W-50 API SN oil.

The Valvoline VR-1 Brett mentioned is also a higher than normal ZDDP oil, and I use it in my Europa S2's Renault engine. It's available in both mineral and full synthetic versions, so read the label. I prefer synthetic for any engine that is already broken-in. It's a fine oil, but Mobil 1 has a higher ZDDP level.

Back in the day, Lotus recommended Mobil 1 20W-50 for the 907/ 910/ 911/ 912/ 920. However, it's ZDDP content now exceeds the API's current maximum limit for automobile engines, so Exxon-Mobil re-branded it as "Mobil 1 20W-50 V-Twin Motorcycle Oil". It's the same great stuff with 1600ppm phosphorus, you just need to shop in the motorcycle aisle.

A similar 'top pick' motor oil is the "BMW TWS Motorsport 10W-60" that BMW requires for warranty service of it's 'M' engines. The 907 loves it, and it's available from your local BMW dealer's parts department. It's a re-brand of "Castrol TWS 10W-60 Motor Oil" that is otherwise not marketed in North America. It's very good, but it's also very expensive... ~$16/ quart.

In the following chart, lines that start out with question marks are bits of information I’ve not yet substantiated, or otherwise just notes to me. I normally edit them out before posting the chart somewhere.

.Phos. / Zinc Current motor oils with high Zinc / Phosphorous (ZDDP) levels:
2400p / 2500z Redline Racing Motor Oils (typical, “all have a min. of 2200 ppm Phos”)
2100p / 2500z Redline Motorcycle Oils
1750p / 1850z Mobil 1 0W-50 Racing Oil (Excellent, and contains full street additive package). <<<<<<<<<<<<<
1660p / 1760z 3 Qts Mobil 1 20W-50 V-Twin plus 2 qt Mobil 1 0W-50 Racing Oil
1630p / 1730z 4 Qts Mobil 1 20W-50 V-Twin plus 1 qt Mobil 1 0W-50 Racing Oil
1600p / 1700z Mobil 1 20W-50 -- old, discontinued, now re-labelled and called…
..................... Mobil 1 20W-50 V-Twin Motorcycle Oil (same great !! stuff) <<<<<<<<<<<<<<<<<<<<<<<<<
1600p / 1700z Classic Car Motor Oil --
__?_p / __?_z Redline Motor Oils street (ZDDP unknown, did not perform up to the hype)
__?_p / __?_z Penrite Synthetic 5, 5W-60 (ZDDP unknown, but excellent oil)
__?_p / __?_z Royal Purple Synthetic with Synerlec (ZDDP unknown, but excellent oil). <<<<<<<<<<<<<<<<<
__?_p / __?_z Royal Purple Racing R51 (ZDDP unknown, but excellent, even better oil). <<<<<<<<<<<<<<<<<
__?_p / __?_z Valvoline Durablend 10W-40 (ZDDP unknown, but out-performs $$$ oils)
1200p / to ..... 1980-88 API SF permitted highest ZDDP levels ever allowed by API,
1500p / ......... with 'phosphorus' ranging from 0.12% to 0.15% (1200-1500ppm).
1400p / 1500z Brad Penn®, Penn Grade 1 Hi-Perf Oils, Excellent hi-perf 'mineral' oil. <<<<<<<<<<<<<<<<<<<
1300p / 1400z Valvoline VR1 Racing Oil, API SF/CD, contains a full 'street' additive package. <<<<<<<<<<<<<<
..................... Available in both mineral & full synthetic formulas, so READ the label.
1300p / 1400z Valvoline VR1 "Not Street Legal" Racing Oil - NO street additives !!
.................... "IF" used on the street, NSL should be changed every 3 months/ 500 miles"
.................... "Not Street Legal" is Marketing Spin, and has nothing to do with the law.
..................... However, it does exceed the upper limit for ZDDP set by the API.
1383p / 1483z 3 Qts Mobil 1 15W-50 plus 2 qt Mobil 1 0W-50 Racing Oil
1310p / 1410z 4 Qts Mobil 1 15W-50 plus 1 qt Mobil 1 0W-50 Racing Oil
1266p / 1379z Amsoil HDD Series 3000 Synthetic 5W-30, combined Diesel / Gasoline.
1266p / 1379z Amsoil ARO 20W-50 Synthetic, street, gas/ Diesel, "for" API SL/ CI-4 Plus
1265p / 1378z Amsoil AMO 10W-40 Synthetic, street, gas/ Diesel, "for" API SL/ CI-4 Plus
..................... Note: “for” API SL applications, but NOT API certified due to high ZDDP
1265p / 1375z Amsoil AHR SAE 60 Synthetic Racing Oil, alcohol/ nitro, super HD race.
1235p / 1370z Amsoil TRO 20W-­50 Synthetic Racing Oil, gasoline hotrod, race, big cam
1200p / 1300z Mobil 1 15W-50 (vintage flat-tappet engines/ Lotus approved).
..................... Meets my 'personal' minimum 1200ppm phosphorus level.
..................... Okay for the street in an engine that's already broken-in.
..................... Not okay for motorsport, autocross, or track days... IMHO.
1200p / 1300z API SM & SN “allow” but do not mandate 1200ppm phosphorus for SAE 40 and heavier oils.
..................... Some brands have the 1200ppm max, others have the 800ppm min.
..................... Nothing on the package label tells you how much ZDDP is in that SM / SN oil.
..................... To me, that's the biggest draw-back to using SL and later motor oils... ya can't tell what's in it.
Sorry about the bandwidth...
Tim Engel

Last edited on 06-30-2017 06:02 pm by Esprit2