Cam and tappet failure = using newer SJ/SM oils

[marcfuller]

There is a very relevant article in June's Hot Rod mag titled "Cam Info You Need, Why are flat-tappet cams getting wasted more frequently these days? You'll be surprised by the answer. " page 124.

It has nothing to do with dino vs syn. - It has to do with the fact that the newer oils particulary SM grade oils (especially Mobile 1) are missing a significant amount of friction modifiers (a zinc and phosphorus compound called zinc dialkyl dithiophosphate (ZDDP)) that are being left out to meet emissions goals. Our old direct "cam on tappet" engines need these ZDDP friction modifiers.

Suggestions include avoid using the latest API certified street legal oils; and instead using Racing Oils, light duty diesel oils like Rotella, or adding a friction modifier additive.

[rgh0]

The issue with phosphate or other extreme pressure lubricants for cams is really only during the initial break in of new cams and buckets until the matching surfaces have been polished to perfectly suit each other.

If you get the buckets and cams phosphate treated, give them a good dose of assembly grease before startup and use a running oil with high levels of extreme pressure additives for the first few hours then you will have no problems if you change to a modern synthetic after that.

Modern agressive cam profiles overloading the cam to bucket interface in older engines is probably as much as a problem as modern lube compositions.

Rohan

[marcfuller]

Rohan, I respect what you contribute in the forum. Have you read the article? The article does seem to have some meaningful data as well as input from cam, tappet and lubrication engineers, and engine builders that leads to somewhat different conclusions for the US. What are ZDDP levels in motor oil sold in Australia?

Regards,
-Marc

[M100]

Interesting reading - this change affects just about every Lotus engine except the Toyota unit in the Elise/Exige! I know someone who has coated the cams and followers of a 90's Elan with DLC (diamond like coatings) although this was done in a no costs considered program to build the ultimate engine (it puts out around 450bhp!)

The Mobil 1 (we only get 0W40 and 15W50) currently sold in the UK and across Europe is manufactured in France but carries similar ratings as the US (API SL/CF) with some additional European only ratings (ACEA A3/B3/B4)

A3 Petrol High performance and / or extended drain
B3 Diesel High performance and / or extended drain
B4 For direct injection passenger car diesel engines

With the current "Euro" Mobil 1 being one step behind on the API grade hopefully it's still providing better protection than the latest stuff.

[1964 S1]

Can I keep using Castrol GTX and not wipe out my cams?

[elandoc]

Hi Rohan,
We've been discussing this very topic in Qld. One of our members is a chemist for BP and we'll hopefully have an article in the June magazine. He has intersting thimgs to say about Ultimate vs Optimax, too.
Patrick

[rgh0]

Hi Marc

All the modern synthetics sold in Australia are imported US formulations so I beleive my experience mirros that in the US. I have not seen the article referred to, is it posted on the web anyware?

My cam and tappet knowledge comes from the work I did over the last few years with cam manufacturers and metallurgists based on a couple of cam failures I had. Lots of variables involved of which oil was only one and relatively low in order of importance I concluded. My experience only truely relates to the Twin Cams I build but for that I know it works.

Things to think about:

1. Cam and bucket metallurgy - cast iron much better than steel and critical to maintain at least a 10 Rc hardness difference between the 2 to prevent galling especially if using steel components. Many modern engines use either steel bucket or steel cams or both. The replacement buckets for Lotus engines these days are steel for example. The old cast iron components were much more resilient

2. Loading on the cam / bucket interface. High lift, high acceleration cams and heavy valve springs put extra loading on the interface. As you play with these you are getting into problem areas especially with older engines. My Toyota Landcrusier with a direct cam and flat tappet design has run for over 300000 kms with no sign of problems on mobil one synthetics the whole time but cams and bucket surface areas bigger than the Lotus and revs and cam profiles much more gentle. My standard road Plus 2 has run close to 100000 km on mobil 1 with no sign of significant cam or bucket wear. My Elan racing engines dont get much more than 5000km between rebuilds but once I sorted out running in and materials I no longer have cam or tappet problems with these despite the high acceleration profiles and heavy valve springs and big rpm.

3. Running in. The most common time for cam and tappet failures is during the first few hours of operation. All the cam manufacturers recommend only using new tappets and cams together and using large amounts of assembly lube. They also often recommend running in for an extended period with light valve springs. Phosphate coatings are important especially if using steel buckets or cams to provide the extreme pressure lubrication required while bedding in. Using a running in oil with high amounts of EP additive ( that why it is a running in oil) also help. Once bedding in is completed EP additives are much less critical

4. Finally and of least significance is the lubricant used once the cam and tappets are run in. In this area all I can say is that modern synthetics reduce the wear I observe in all parts of the engine compared to other oils and that they also keep the inside of the engine much cleaner and are much more tolerant of high temperatures. I cant tell if changes in synthetics in the last couple of years have been detrimental compared to synthetics of 2002 or 2003 vintage but the difference is small enough not to be noticeable in my engines and it certainly has not caused catastrophic failure in any of my flat tappet direct cam engines from full race to mild road and they represent a fair cross section of the types of engine around ( 1 toyota, 1 jag XJ6, 1 esprit, 1 road twin cam, 2 race twin cams)


Could current low EP additive synthetics cause problems in a hot rodded engine that has not been properly modified and run in --- probably. But are they the real root casue problem -- probably not in my humble opinion.

regards
Rohan

[marcfuller]

Rohan,

The June 2006 Hot Rod article addresses the large increase in cam and flat tappet failures realized in the last three years and at this time I have not found it on-line. PM me your email I would be glad to send you a copy. Hot Rod attributes the rash of failures to mainly two recent changes; flat tappet quality, and the reformulation of oils reducing ZDDP. This has nothing to do with syn vs dino they both are reducing ZDDP. Recent research into the molecular nature of ZDDP has shown that there is not a good pressure lubricant substitute to take the place of ZDDP. ZDDP in the SM oils is now less than 1/2 what it was in the SG oils. Projections call for ZDDP to be further reduced in US formulations. To illustrate the drop in ZDDP i have included a chart from the article-

[DJThom]

I've read as much as I can on this forum and elsewhere regarding ZDDP and engine oil run in. For my Elan, I've used Castrol SAE HD 30 with GM EOS additive. I've run the engine less than an hour total, and have only driven it for one short trip at low RPM.

How soon should I change the break-in oil, or should I change it right now before any further driving?

[rgh0]

I change from running in oil to synthetic oil in my race engines after completing my normal running in routine which takes around 2 hours of running. For a road engine I would change after around 1000 km's.

regards
Rohan

[rgh0]

I just finished doing a service on my Landcruiser. It has done 160,000km total and around 100,000 km on the new spec low ZDDP Mobil 1. It has a flat tappet twin cam engine that according to the reports is suspectible to problems with lack of ZDDP.

Zero wear or damage to the cams and tappets when I checked it today. Incidently valve seat recession measures less than .001 inch per 50,000 km also.

I continue to see no evidence in the engines I work on for problems using modern synthetic oils with Lotus twin cams or engines of similar design doing many more Km's than any twin cam does these days. However it remains critical that engines are run in correctly and use correct metalurgy in their cams and followers as it always did.

Push rod engines with followers on top of the cams ( eg American V8's and MG engines) may suffer bigger problems due to poorer lubrication especially when fitting high lift cams and heavy valves springs but fortunately I avoid working on these.

cheers
Rohan

[twincamman]

I have been using diesel oil in both my twin cams and my vee and my renault europa motors for the last 2 years with good results --cam wear on a new mgb race motor tiped us off --when the cam supplier told us to call our oil supplier when we complained about 6 percent wear after one race event last season -ed

[rgh0]

Hi Ed

Interesting to see the engine you had a problem with was a B race engine , these sorts of push rod race engines are the ones I hear most about for cam to tappet failures and I believe it is due to a number of factors not just the oil used.

I have not yet seen it happen on a road going twin cam using modern synthetics.

I have seen it happen 3 times now on twin cam race engines and each time the cause was attributable to cam and bucket metalurgy and running in procedures followed. Once those were sorted out and a high ZDDP oil used during running in, it made no difference from a cam wear perspective if a low ZDDP synthetic oil was used after the running in period.

Did you check out whether any of the other possible failure causes listed in my post in April last year in the topic were also contributory to the cause of failure of your B engine?

cheers
Rohan

[twincamman]

it wasnt my engine --one out of the race shop --but I have driven the car ---the only wear was the cam lobs --,y first attempt at synthetic oils [castrol]cost me a rebuild on tc out of my 7 spun #3 con rod bearing -----so I have used deisle with great success ever since ------ed