Re: Engine oil (for european cars)
 

Yes that will be fine for your LT5.

Graham

Re: Engine oil (for european cars)
 

Hmmmmm.....:p

It seems Mobile 1 10W-30 being fine is debatable......phosphorus 800 and Zinc 900...
I am sticking with Amsoil 10W-40 with Phosphorus 1265 ppm, Zinc 1378 ppm.
I suppose it depends considerably where your RPMs are most of the time among other issues...

I suppose it also depends on how the catalytic converters behave with various oil chemistry.

Re: Engine oil (for european cars)
 

Interesting opinion, what specific design parameters of the LT5 make it require high zinc and phosphorus.

graham

Re: Engine oil (for european cars)
 

Unfortunately here in Italy we must choose between few mobil1 oil type. I usually use the zr1 with normal drive, never track day since 2007...Now i'm using a common 10w40 oil...
So, i decide to use the mobil 1 5w30 ESP FORMULA that's available here in europe, and i want to put the "Ceramic Power Liquid" treatment.
By doing this anti-friction treatment I will be protected as if I had put amsoil and it lasts 100000km

Re: Engine oil (for european cars)
 

The design issues that come to mind are valve spring pressure (including variable spring load and variable Valve and Lifter inertial load) and all at up to 7,000+ engine RPM.

You have the "Theory".....I have the "Cams"......

https://cimg2.ibsrv.net/gimg/www.cor...ed5dc43cc.jpeghttps://cimg1.ibsrv.net/gimg/www.cor...637964776.jpeg

Just being on the safe side given all the Expertise and Discussions regarding LT5 Engine Oil on this and other Forums :handshak:

Re: Engine oil (for european cars)
 

Once again, interesting.
The LT5 has relatively low contact pressure at the cam/tappet interface <120,000 psi with stock parts. Spring loads are around 100 to 115 on the seat with 235 to 250 open, with stock lift. Whereas the flat tappet engines that require extra additives are typically between 200,000psi to 300,000 psi.
7000 Rpm is not really high rpm, mean piston speeds less than 22m/sec, once again with stock parts.
Oh and I might have seen a cam or two over the last 33 yrs.

Graham

Re: Engine oil (for european cars)
 

Actually, none of the recommendations from legitimate sources that I've found really specify the use of high zddp/zdtp oils based on cam lobe contact pressure. Most are based on the use of flat tappet cams in general. The critical factor for the LT5 is the relatively long cranking time before oil pressure is generated. That zinc and phosphorus is the only thing protecting those surfaces before oil is supplied. The longer a car sits, the less oil remains on those surfaces. Some of our cars sit for extended periods of time.

The other place the zddp protects is during high RPM runs where the oil film strength may be at its limits or exceeded.

Even companies like Valvoline make vague comments like "The controversy exists as a result of many hands-on car enthusiasts and engine experts belief that lower levels of zinc in API SN and SM motor oils can cause excessive wear in older style push-rod and flat-tappet engines. They hold this belief despite the fact that all new motor oil classifications are intended to be backward compatible."

Yes..."intended." We know for a fact that an oil with zddp provides more protection than an equivalent oil without it. That is chemistry and physics. So it comes down to whether or not a person believes that all the new more modern additives and polar adhesion innovations trump the zddp. Most people, including those very knowledgeable on the subject say no. Let's face it, the zddp wasn't removed because there were better chemical compounds, they were removed due to their suspected long term damage to catalytic converters and the manufacturer's necessity to guarantee those components for the life of the vehicle.

I am the internal quality manager at a facility that builds flat tappet, pushrod, aircraft engines. They live their entire life below 3500 rpms and we still recommend that people run a zddp additive in every engine we build.

https://www.aircraftspruce.com/catal...SABEgKMUPD_BwE

Re: Engine oil (for european cars)
 

Thanks for your input

Since contact pressure is the main driving force in terms of film shear and therefore wear, it is very iimportant.

The LT5 has some advantages with respect to retention of lubrication at star up since it has an iron to iron contact at the cam to tappet interface.

You would be surprised at the amount of oil retention at this area even after years of standing idle.

If the oil film is broken down at a bearing interface it is due to poor design or operating outside design parameters, so I understand placing as many band aid as possible.

The original question was pertaining to the use of a certain oil in a stock LT5 with 25 k miles, in the context of the question the answer is yes.

Now if we wish to discuss modified engines, extreme use or other extenuating circumstances, then the answer may be different.

At the end of day there are many opinions, all I have is facts having evaluated and reported on most of the lt5 engines following many very arduous durability tests that led us to release for production in 1990 and 1993 MY.

Graham

Re: Engine oil (for european cars)
 

:happy1:
H

Re: Engine oil (for european cars)
 

Hey, save some of that popcorn for me would ya.

Thanks

Graham