The new proposed GF-5 oil specifications have finally come out of committee and are up for a vote by the ILSAC membership. The proposed changes are already a year behind schedule as the new GF-5 was supposed to be introduced into the 2010 model year cars(lack of agreement concerning Motor Oil? who would have thought). The change was mandated by the vehicle manufacturers in response to CAFÃ‰ (corporate average fuel economy) standards slated for implementation in 2016. Emission standards and warranty requirements have new standards as well. Some things will stay the same while others will change. One of the biggest changes that you will see is the new SAE 0w-20 motor oil, the other usual SAE viscosities will still be there such as 5w-20, 5w-30 and 10w-30.
In my review of the proposed GF-5 specifications the zinc and phosphorus levels have changed from a recommended 800PPM.under GF-4. The proposed GF-5 calls for maximum of 800PPM to a minimum of 600PPM. This amounts to a reduction of about 100 to 300PPM from the GF-4 levels as many GF-4 oils were above the 800PPM of zinc. I would hope that the zinc levels would stay around 800PPM, but the ILSAC specifications do not call for oil formulation (that is left up to oil manufacturer) but specify oil performance and passing the testing instead. To be fair the vehicle manufactures were admit about maintaining backwards compatibility in motors oils, however I do not think that they were thinking about as far back as I am thinking. What levels of zinc will be in the new formulations? It is too early to tell as they have not even began to test yet.
Modern vehicles can survive on reduced levels of zinc because the high unit loading of flat tappet cams have been replaced by roller tappet cams and the sliding action of pushrods and rocker arms have been replace by overhead camshafts. The less well know effect that is happening in modern engines is the polishing of all contacting metal surfaces. In essence the rougher the surface the more zinc that is needed to guard against metal to metal contact. Modern engines can get away with less zinc simply because of the polished metal surfaces. Remember that zinc is a sacrificial chemical that goes to work under heat and pressure, once it is used up (IE protecting the camshaft) it is gone and the oil needs to be changed to replenish the zinc levels.
The other important fact about ZDDP is that it is an excellent corrosion inhibiter (since 1941) that protects the engine from rusting internally when it sits for long periods of time. Modern cars with their aluminum and plastic components do not have as much of a problem with corrosion. Our tractors many sit idle for extended periods of time and I think corrosion protection is very important.
Detergents in motor oil perform a very good job cleaning up after sludge, varnish and deposits but they also remove the sacrificial zinc plating as well. There has to be a balance between detergent and zinc levels. I believe that going forward that this balance will be interrupted not to the detriment of the modern engine but the older engine will suffer the consequences of have more detergent than zinc in the formulation.
The research for this article has been difficult, as there seems to be a lot of hype from companies promoting their products. The other end of the spectrum involves reading research briefs that too many people (including myself) view as over the top technical in language and can not be digested in casual reading. The good middle of the road information is not very comprehensive and contains only a few relevant points and a lot of hype. This has been frustrating to reference sources as there would be too many to site effectively and that would frustrate interested persons. Good News!!on December 29 Joe Gibbs Racing oil updated their web site and it contains a wealth of good relevant information that is easily accessed. I would encourage interested persons to explore this site. It contains very good information on this topichttp://www.joegibbsracingoil.com/traini
Joe Gibbs of course has his own oil and it looks like good stuff, however it is easily double the price Shell Rotella 10w-30. How will the changes coming in motor oil play out? That will remain to be seen. But from now to 2016 when the new fuel mileage standards (CAFÃ‰) kick in you can bet that every little thing will be examined several times over in order to attain this difficult plateau. Motor oil may will change a couple of times by the time 2016 arrives. For myself I plan on staying with Shell Rotella 10w-30 (also 15w-40 or 30wt) in the interim as it offers the best protection for older engines at a reasonable price. I currently know of no plans to update the API CF-4 category that Rotella is part of.
I still do not believe that the sky is falling, at least not now, however awareness followed by an exercise in diligence will keep the coming changes (GF-5) from adversely impacting our hobby.
More information about GF-5 and the proposed changes can be viewed at http://www.gf-5.com/
Resources for further information,http://www.jameshalderman.comhttp://www.joegibbsracingoil.com/traini
My thanks to everyone that contributed,