ZDDP REDUX

[why]

It seems that this came up a few years ago. There are many websites that say ZDDP is not necessary for an already broken-in engine, and others even question its use ever other than in high-loading engines. As I recall the only sites recommending the additives are sites that sell it or have some other commercial relationships behind their promoting it.
Jay
'65 3000

 

[red57]

My understanding is the issue is flat tappet engines, not whether the engine is 'broken in' or not. The zink and other additives were common when we all had flat tappets, now that all use roller tappets the zink has been removed to prolong catalytic coverter life span as mandated by our government. I'm not aware of any other parts of the motor that require zddp but the extreem pressure and friction of the flat tappet does.

 

[Keoke]

Why:
just stay with the old heads that know these flat tappet engines and you will be OK--Keoke

 

[57_BN4]

Lots of modern engines use flat tappets. Most high performance motorcycles do for sure. The difference is that the materials are much more refined and the heat treatment processes are far better.

The old cast iron cam/lifters are very soft compared to modern stuff and rely on various boundary lubricants that I can't even pretend to understand. A modern cam will run for quite a long time with no oiling at all. The instructions for checking oil pressure on a YZF250 dirt bike are to run the engine at idle with the oil feed pipe removed from the cylinder head. If no oil comes out of the pipe after one minute then stop the engine and find out why. They get virtually no oil but rarely give trouble.

A further evidence of modern materials is that there is no cam break in procedure for modern cams, or at least in our workshop there isn't. It is quite normal to swap an exhaust cam to the inlet position and vice versa to change the torque profile of the engine, in this instance a V8 made from two Kawasaki 1200cc 4 cylinder bike engines.

Andy.

 

[Randy Forbes]

Interesting, and makes me comment on the BMW S-54 engine, as fitted to the M3 2000-2006, Z3/M 2001/2002 & Z4/M 2006-2008. This engine requires the use of a specific Castrol RS/TWS 10w/60 oil. It has a flat-tappet DOHC layout.

A lot of the owners of the aforementioned cars gripe about the price of the oil, at $13.95/ltr (but yet they buy $50-60k cars__go figure). I buy this oil regularly by the case for the cars I work on, maybe I should start running it in the Healey too...

 

[Bob_Spidell]

Randy,

Any idea why BMW specs such a viscous oil? The trend seems to be lighter oils (like 5W-20).

 

[Michael Oritt]

Lighter oils=better MPG

 

[Bob_Spidell]

Lighter oils=better MPG

Right. That's why I wondered why BMW specs such a 'heavy' oil. Wondering if this might be a good weight for Healeys (if you can afford it).

My Mustang calls for 5W-20. I was a little concerned at first using such a 'light' oil--heck, 3-in-1 oil is 20W--but I checked the forums, etc. and from what I can gather this is an excellent oil and anything heavier might even damage the engine.

 

[Randy Forbes]

That oil was only spec'd for the S-54 (3.2 Ltr I-6) and S-62 (4.0__I think__V8); both were "true" BMW ///Motorsports division engines, so they may not have cared about the fuel mileage, just engine longevity.

When the S-54 was first released (model year 2000 in M3s, M-Y 2001 for Z3/M Coupes/Rdstrs), there were 5w/30 oil stickers on the radiator cowl, and they made a big deal about recalling them (on the 1st included maintenance oil change) about changing them. It was a source of confusion thereafter about which oil was "correct" (the 10w/60 is correct). By the time my car was produced, 08/2001, they were wearing the 10w/60 oil sticker.

 

[steveg]

FWIW - I like Valvoline VR1 - back when this topic was hot I called Valvoline on the phone and spoke to an engineer. He told me VR1 was basically the oil they used to sell when everybody used the zddp oil and they'd tagged it as 'Racing' to let people know it wasn't for street cars anymore. He said it had all the zddp they used to use back in the day.

 

[vette]

10w-60, being the multigrade that it is, would mean that it is only the thickest when the temp is very hot. Maybe that would be good for everybody. I have read that using a thicker oil than specified in one of the new GM LS engines would be detrimental to its performance because the variable cam technology (uses the oil pressure and viscosity to retard and advance the cam, higher rpms = more pressure = repositioned cam timing) and other factors have been engineered for the specified viscosity.(thicker oil literally would screw up the timing to the point of braking things like valves and pistons). Along time ago I read a NASCAR engine builders book where he said that too much oil up to the valve train in the heads reduced performance and sucked horse power. He ultimately established what he considered the ideal amount of oil and oil pressure at the rockers. He said 10psi for every 1000rpms. (this would have been for an overhead valve v8).
Latest articles I have read are now saying unless you have built an engine with very high cam angles and very heavy springs to keep the followers on the cam lobes at high rpms, the ZDDP and the like is not really necessary. Of course alittle prevention might well be worth the cure. On my '70 vette, 350cu in/350hp, not base engine, which has never been out of the car or rebuilt in any way, I have been running standard 30w oil for 27 years and the engine shows no ill effects.