355 reccommended engine oil

I am using Motul 300V 10w40, works great, some odd engine sound in second bank at idle went away when i changed from M1 5w40, could be because Motul is based on esther.

 

Could also be because Motul 300V 10w40 has about 30% higher ZDDP content than M1 5w40.

 

You could always use teh Shell lubematch....

https://www.shell.com/motorist/find-the-right-oil.html#iframe=L21vdG9yaXN0L2ZpbmQtdGhlLXJpZ2h0LW9pbC9famNyX2NvbnRlbnQvcGFyL2lmcmFtZWRhcHAuc3RhdGljL2lmcmFtZS5odG1sIy9nYi9lbi1nYg

 

That makes sense. The XT has BMW LL-01 approval, same as the Ferrari approved Pennzoil ultra 5w-40. All oils with the BMW approval LL-01 will have an HTHS of 3.5 or greater, appropriate viscosity range and shear stable.

 

Shell lube match says Helix Ultra Racing 10W-60. Never seen greater than 50 recommended.

 

Ins't that oil designed for shot distance racing not for passenger cars for thousands of miles?

 

That's what it recommended for my 348 (IIRC it used to be somthing like 5w 30 or something) but since changing over to the 10w-60 my cam cover leak has been reduced considerably Either that or Ive run out of oil!!!! ;-')

 

I don't know if oil that thick will flow quickly enough to fill the spaces between the crank journals and main bearings for normal passenger cars? Race cars running real hot perhaps yes, but normal driving, not so sure? Does the car run hotter by chance?

 

Wonder how much HP is lost pumping thicker oil and over coming the additional friction?

 

Virgin oil analysis? (additives diminish with use)

 

Is ZDDP still considered important? I was under the impression by (people much more knowledgeable than me) that there are many other additives in modern motor oils that sufficiently take the place of ZDDP that it is no longer a concern. I was thought ZDDP is now more of a novelty product for niche players in motor oils to cater to the faithful... Am I wrong?

 

Unclear whether anything else is as effective as ZDDP. What is clear though is the substitution occurred to protect catalytic converters.

What you heard might have been for modern engines. I'm not taking a chance with this engine.

 

Both tests were performed on new oil (see the attached test results).

 

One engine oil that I have confirmed the ZDDP content with the manufacturer's tech. department is:

Amsoil Premium Protection 10W-40 Synthetic Motor Oil, Phosphorus: 1,265, Zinc: 1,378. Perfect for flat tappets I think (and it says "High Zinc Formula" and "Flat Tappets" on its label).
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This is what I am going to use when I finish my current stock of another engine oil with similar ZDDP content (which is otherwise no longer available in Malaysia).

Incidently, AMSOIL Severe Gear 75W-90 oil has scored top results in comparison with many other well known gearbox oils (except Motul, see the attached White Paper).

PS. I am not working for Amsoil.

 

Exactly, i noticed that there was considerably less leak from the valve covers when i changed to 10w40.

 

Several years ago I read a research paper on ZDDP, how much protection it gave and how long it lasted. The conclusion was that over time the ZDDP breaks down, like any additive, and the protection is lost. How long protection lasted was a matter of the initial ZDDP content. All the oils tested provided sufficient protection initially. Higher levels just protected longer. Considering that typically we change oil in our 355 very year after less that a couple of thousand miles, I wouldn't think any reasonable ZDDP content would make a difference. 900 to 1500 ppm will both protect for that length of time. I'll look for the paper again. I know it's on one of my computers but which one and in what folder?????

 

AMSOIL Severe Gear 75W-90 is a great oil but my 348 GB was awful , hard to pull out of gear it would pop out instead of sliding out, 2nd caught teeth shifting into etc etc. It was an awful driving experience. The current shell rotax is far far better in my GB at least, never an issue going out of gear and 2nd gear is usable before it warms up with no teeth catching.

Amzoil also makes a zrod oil packed with zddp.

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Keep in mind that study was paid for/done by Amsoil so take that into consideration interpreting the results.


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There is an Affidavit attached at the end of the document as to the correctness of all test results. And if not for Amsoil, the test results shown for all other brands must be correct. Otherwise, Amsoil would have been sued big time by the other companies.

 

Here is a question- I am not the smartest guy so please bear with me.
My car says recommended oil is 10W-40.

Why is everyone running 5W-40 (including me)?

Is it because the car was designed around traditional oils and not synthetics?

I either have a cam seal or cam cover oil leak and I am wondering if a slightly thicker oil will solve it.

 

F355s were spec'd with synthetic oils in mind. Oils start out thick when cold, and thin when hot. The car requires 40 weight. The lower number is for cold starts, as thinner oil flows to vital engine parts faster. So understand that your oil is a thickness of 10W, then THINS to a 40. So at operating temperature, all things being equal, 0w-40, 5w-40, and 10w-40 should all perform similarly. The advantage of a 0w-40 or 5w-40, is it will flow better at cold start over a 10w-40. Don't try a "bandaid" with thicker oil, I tried Mobil 1 15w-50 once and at cold start the oil pressure was super high...scary high. I dumped it a few days later and put in the proper viscosity range. If you have leaks, get them fixed, or live with them.

 

Thank you f355spider, I agree. I do not want to band-aid anything. I will fix this oil leak, the right way, period. I am currently building an engine stand to pull the engine. I am not sure if its the cam seal or the cam cover gasket but there is a slight leak that shouldn't be there. Since I am pulling the engine I am going to have to change the oil and I want to find the best oil for this car, period. I am currently looking at Amsoil Z-ROD 10W-40 Synthetic Motor Oil for its high Zinc content although I am not sure how its different from Amsoil Premium Protection 10W-40 Synthetic Motor Oil. I am wondering if the slightly thicker oil will help or even eliminate this leak? It probably wont but I can't help but be curious. I don't think my car leaked until I filled it with this Pakelo Krypton XT 5W-40 oil, but it is completely possible it was leaking before and I never noticed it as it was so slight.

But still... Why are we all using 5W-40 when it even says ON the car to use 10W-40?

 

Z-ROD 10w-40 and Premium Protection 10W-40 appear to be very similar except that Z-rod has a bit higher ZDDP:

Z-ROD 10w-40 - Phosphorus 1320, Zinc 1440

Premium Protection 10W-40 - Phosphorus 1265, Zinc 1378

Otherwise, the difference between 10w-40 and 5w-40 is that, of course, 10w has higher viscosity than 5w when cold. However, even thought their second numbers are the same, 10w-40 has also slightly higher viscosity at engine operating temperatures.

Example Amsoil viscosities at 100C:

10w-40 - 14.6
5w-40 - 13.6

 

Thanks! I noticed you wanted to use the Premium Protection instead of Z-Rod. Why?

 

Because there is little downside to the practice, and you potentially gain better flow on cold start, possibly reducing cold start wear. In addition, 10w-40 is no longer the recommendation of Ferrari, 5w-40 is the preferred and recommend oil from Ferrari for close to 20 years.
When I did my own oil changes on my 355, I would often use Mobil 1 0w-40. It had good HTHS of 3.6. Its viscosity at 100c was lower though...around 13.1 or so at the time (8 or 9 years ago). Not sure if the specs have changed.

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