Which Engine Oil?

[Mike Smith]

I did swear years ago that I would not get involved in Oil discussions – It is an extremely complex subject, confused by the different needs of different types of engines, government regulations and sales marketing ploys.

However, as many of you already aware, the reason that oils with high quantities of Zinc are essential in a 356 engine is that we have 2 x Flat Faced Cam Followers which run on a Single Cam Lobe. This is a high pressure point, affected by the Cam Profile, Lift and Spring Set-up. Zinc acts as a lubricant and cushion, in this important area.

Of course, changing the oil frequently is preferable thing to do but first select the correct oil and then and more importantly, install a proper Filtration system.

The existing system is a by-pass system and arguments abound about how much oil actually goes through the filter although between 8% and 10% seems to be the favoured amount (I have never attempted to work it out)
That means that approx. 90 % of the oil goes straight to the bearings carrying with all the impurities that build up inside the engines

This is quite a good read - http://www.vmrcars.com/OilNewsletterArticle.pdf

See what you have started now - 356monkey

[neilbardsley]

I would agree, that is a very good idea.

Yes of course when I think of very experienced 356 people you are the first the Mike that comes to mind Are you ever going to turn up at an event so you can take the p*ss out of me in person?

[Mike Smith]

One Day Neil - One day

[mycar]

Yes the Neil, one day we will.

[Ashley James]

Most engines have flat tappets though modern cam profiles are kinder and oils sold for racing or old engines tend to have high a ZDDP content.

I hate arguments, particularly forum ones, but it is important to stress that fully synthetic oils are significantly better than old fashioned mineral oils.

Many years ago I actually phoned and spoke to two separate oil company chemists to be sure I’d got my facts right.

[Mike Smith]

There you are!

I should have followed my own rules and not got involved

[majordad]

I’ve akways worked on the rule that oil is cheap relative to an engine, but I admit at times I’ve forgot that by accident or neglect.

[jb]

If I had a 356 I would seek advice from the 356 experts and do whatever they recommend.
So I would do as Mike says.
However I doubt if it makes much difference if you are going to religiously change the oil after 1500 miles and don't race it.

[mycar]

Agreed. All I would add is that although fully synthetic oils {both engine and gearbox} are undoubtedly superior to their mineral forebears, they will make their way past our ancient seals and case plugs and deposit themselves in small amounts in your engine bay and on your garage floor.

[Hendrik Moulds]

I would agree, that is a very good idea.

Yes of course when I think of very experienced 356 people you are the first the Mike that comes to mind Are you ever going to turn up at an event so you can take the p*ss out of me in person?

Ahh, I would love to be there for that. Your hot starting comment from just after you joined DDK still makes me chuckle.

Agree about the synthetic oil too Mike.

[Ashley James]

Agreed. All I would add is that although fully synthetic oils {both engine and gearbox} are undoubtedly superior to their mineral forebears, they will make their way past our ancient seals and case plugs and deposit themselves in small amounts in your engine bay and on your garage floor.

That is categorically wrong as explained in the Mobil 1 video I posted.

As I keep saying there is good evidence that fully synthetic oils are much better than old fashioned mineral oils. This is why they’ve been endorsed by motor manufacturers and new Porsche’s come with them. They virtually eliminate wear.

In my opinion they are a better choice for older engines that are harder on camshafts and top piston rings and whose temperature control is less good. I explained why this would be true when I posted the benefits previously. I’d verified these with chemists from Shell and Mobil when I phoned them more than thirty years ago.

I have the greatest respect for PRS, they’ve been fantastic for me and I recommend them whenever the opportunity presents, but I still believe a synthetic racing oil would be a better choice in old Porsches. However I also don’t believe it’s worth arguing about and I’m sure VR1 is a good oil.

[neilbardsley]

Agreed. All I would add is that although fully synthetic oils {both engine and gearbox} are undoubtedly superior to their mineral forebears, they will make their way past our ancient seals and case plugs and deposit themselves in small amounts in your engine bay and on your garage floor.

That is categorically wrong as explained in the Mobil 1 video I posted.

As I keep saying there is good evidence that fully synthetic oils are much better than old fashioned mineral oils. This is why they’ve been endorsed by motor manufacturers and new Porsche’s come with them. They virtually eliminate wear.

In my opinion they are a better choice for older engines that are harder on camshafts and top piston rings and whose temperature control is less good. I explained why this would be true when I posted the benefits previously. I’d verified these with chemists from Shell and Mobil when I phoned them more than thirty years ago.

I have the greatest respect for PRS, they’ve been fantastic for me and I recommend them whenever the opportunity presents, but I still believe a synthetic racing oil would be a better choice in old Porsches. However I also don’t believe it’s worth arguing about and I’m sure VR1 is a good oil.

I wonder if sometimes people blame oil leaks on synthetic oils because they are often of a lighter weight?

[Mike Smith]

Interestingly - Shell were the only people that I am aware of that actually tested their oils on a 356 Engine

It was a Super 90 and that was over 50 years ago

I Believe ???? they recommended Rotella at that time

Wish I could find the bloody correspondence

[Ashley James]

Agreed. All I would add is that although fully synthetic oils {both engine and gearbox} are undoubtedly superior to their mineral forebears, they will make their way past our ancient seals and case plugs and deposit themselves in small amounts in your engine bay and on your garage floor.

That is categorically wrong as explained in the Mobil 1 video I posted.

As I keep saying there is good evidence that fully synthetic oils are much better than old fashioned mineral oils. This is why they’ve been endorsed by motor manufacturers and new Porsche’s come with them. They virtually eliminate wear.

In my opinion they are a better choice for older engines that are harder on camshafts and top piston rings and whose temperature control is less good. I explained why this would be true when I posted the benefits previously. I’d verified these with chemists from Shell and Mobil when I phoned them more than thirty years ago.

I have the greatest respect for PRS, they’ve been fantastic for me and I recommend them whenever the opportunity presents, but I still believe a synthetic racing oil would be a better choice in old Porsches. However I also don’t believe it’s worth arguing about and I’m sure VR1 is a good oil.

I wonder if sometimes people blame oil leaks on synthetic oils because they are often of a lighter weight?

They’re lighter on start up, which is good because they get everywhere quicker and heavier when hotter which is also good because they don’t break down so easily.

In a 356 you’d probably pick the Mobil 1 10w60 which has the extra ZDDP considered necessary for old or racing engines. I think Porsche recommend Mobil, but I’m sure a Valvoline (any) equivalent would be just as good.

[mycar]

One option would be to go to the source.

"The engine is the heart of each and every Porsche, and air-cooled flat engines place particular demands on a lubricant. In short: not just any engine oil is suitable for older flat engines. The development of an engine oil for classic air-cooled flat engines has therefore been like a balancing act between tradition and innovation: as advanced as possible and as traditional as necessary. Although modern oils are better from a technical point of view, this is not the case when it comes to classic air-cooled flat engines. For example, the low viscosity of a 0W-30 oil can result in leaks in a 356 engine, because of the higher production tolerances at the time these engines were produced."

https://www.porsche.com/uk/accessoriesa ... /motoroil/