Why not to use cheap oil in your 8V

[pete roper]

OK, so I've got a warranty job coming in . A bloke with an 8V Griso with a pinhole pourosity in the head casting so it's a new head for him. This actually arrived within a fortnight, I was very impressed. while I had a new, clean, head in my grubby little mits I tought it would be a good time to have a squizz at it and find out what's what.

 

Now we know from the publicity blurb that the engine is Air/Oil cooled and has two oil pumps, one for lubrication and one for cooling. Certainly when the motor is running large amounts of oil gush out of the camboxes and rockers and flow down overe the head to cool it. Run an 8V with the rocker cover off and you'll be drenched in oil in seconds!

 

Having the head off the bike and clean though allows you to see some other much more important things.

 

 

As you can see there is a gallery drilled through the casing by the exhaust valves. There is another one that comes in from the port side of the valves as well.

 

 

Here you can see the two plugged drillings in the casting for the lower gallery in the bottom LH corner of the pic.

 

 

You can see here the boss the gallery is drilled through in the casting.

 

 

Looking at the underside, (Combustion side.) of the head you can see on the exhaust side, (Bottom of the picture.) the two drillings, presumably one a delivery and one a return, in the head. They are the two smaller holes adjacent to the stud holes. The longer slots are part of the oil return for the lubricant that gets flung around and pumped out of the cam boxes/rocker gear above the head.

 

 

Another pic looking at the exhaust port showing the second drilling for the cooling oil feed.

 

 

Looking at the valley side of the head you can see the lubrication oil feed. That is the hole at the front of the head in line with the exhaust stud. This feeds oil into the upper forward stud hole.

 

 

bottom right in this pic, where it is fed up the stud and into the cam bearings in the cam box.

 

 

as you can see from the pic that stud is doweled to the barrel to ensure that there is room for the oil to flow up to the bearings through the stud hole when the stud is centralised by the cam box casting.

 

The important thing here though is that the exhaust valve seats and the head immediately surrounding them is being cooled by a high volume of oil that will be being pumped through the galleries surrounding the seats. The temperatures in tat area are going to be the highest in the motor and using an inferior oil is going to lead to all sorts of horrible varnishes and deposits building up in those, quite small, galleries. when the factory recommends a very expensive, high quality full ester synthetic for the 8V it's not so much for the tappets, (Although protection there is a bonus.) it is because of the oil's ability not to degrade at much higher temperatures than a 'Free Grandfather Clock with Every 4 Quarts' mineral oil from Wallyworld.

 

Ignore the spec at your peril, and yes, any half way decent mechanic will be able to see the deposits and know what they are if the galleries do clog up and you drop the head off a valve. (BFG. This is particularly relevant to you as the 'tard who has been working on your bike has been swearing by Yak Fat. I'd drop it out yesterday, if not sooner, and put something better in!!!!) If I got one in with that sort of problem I'd be sending an oil sample off for analysis and if it wasn't the 'Good Oil'? Bye-Bye warranty!

 

Pete

[belfastguzzi]

and if it wasn't the 'Good Oil'? Bye-Bye warranty!

Great bit of photo exploration/explanation.

 

Now, that's an interesting question. Where does the warranty stand in a situation like this?

 

The handbook says to 'use 10-60 synthetic'.

 

The MG Authorised Service Guy says: "10-40 semi is perfect for everything" and that's all that he uses.

 

The importer, Piaggio UK Aftercare say: "your Dealer Guy will look after the bike. Full Stop. What do you know? And internet forum chat is all rubbish talk by fools."

 

So the upshot is that 10-40 semi-synth is 'authorised' by the Guzzi system and my bike has been running it for the past year.

 

What would they say / could they say regarding Warranty cover?

[pete roper]

Great bit of photo exploration/explanation.

 

Now, that's an interesting question. Where does the warranty stand in a situation like this?

 

The handbook says to 'use 10-60 synthetic'.

 

The MG Authorised Service Guy says: "10-40 semi is perfect for everything" and that's all that he uses.

 

The importer, Piaggio UK Aftercare say: "your Dealer Guy will look after the bike. Full Stop. What do you know? And internet forum chat is all rubbish talk by fools."

 

So the upshot is that 10-40 semi-synth is 'authorised' by the Guzzi system and my bike has been running it for the past year.

 

What would they say / could they say regarding Warranty cover?

 

If your importer says 10/40 semi synth is fine then maybe it is. The factory spec is a 10/60 full ester synth. When I see what the oil has to put up with, (Exhaust gasses exiting the port will be in excess of 1000*C if memory serves me right.) I'm not going to experiment. I'll stick with a full ester synth 10/70 that meets or exceeds the factory spec because I know that one of its most important characteristics is its ability to resist heat induced breakdown that occurs in mineral oils when they are over-taxed.

 

Pete

[belfastguzzi]

If your importer says 10/40 semi synth is fine then maybe it is. The factory spec is a 10/60 full ester synth. When I see what the oil has to put up with, (Exhaust gasses exiting the port will be in excess of 1000*C if memory serves me right.) I'm not going to experiment. I'll stick with a full ester synth 10/70 that meets or exceeds the factory spec because I know that one of its most important characteristics is its ability to resist heat induced breakdown that occurs in mineral oils when they are over-taxed.

 

Pete

Well no, the importer hasn't said that 10/40 semi is ok. However I'm arguing that the effect of their attitude is that they have authorised it, even if they are wrong.

 

The Dealer uses it, perhaps because he is careless and he just uses the one barrel for everything that passes through the workshop.

The Importer endorses whatever the Dealer does, perhaps because he is just careless too.

It doesn't make them right. It doesn't mean that the bike is being looked after properly.

But it's not my choice to use that oil and if the MG guys don't listen to me, then they can't refuse Warranty on the basis that the wrong oil has been used?

[pete roper]

Well no, the importer hasn't said that 10/40 semi is ok. However I'm arguing that the effect of their attitude is that they have authorised it, even if they are wrong.

 

The Dealer uses it, perhaps because he is careless and he just uses the one barrel for everything that passes through the workshop.

The Importer endorses whatever the Dealer does, perhaps because he is just careless too.

It doesn't make them right. It doesn't mean that the bike is being looked after properly.

But it's not my choice to use that oil and if the MG guys don't listen to me, then they can't refuse Warranty on the basis that the wrong oil has been used?

 

Yup, your logic is impecable, doesn't mean they are right, but what woiuld I know, I'm just some bloke on the innerneck....

 

Pete

[dlaing]

Yup, your logic is impecable, doesn't mean they are right, but what woiuld I know, I'm just some bloke on the innerneck....

 

Pete

Just a bloke on the innerneck? Dude, you are Pete Roper! and you just pointed out how close the oil runs to the exhaust valve.

I'll take it you won't run Yak Fat in those engines?

There is no way I would run that engine with anything that was not designed to handle that heat.

Note that Full Synthetic is not necessarily a full ester synthetic.

The difference between a 10W-50 and a 10W-60 is only ten degrees, but the flash point differences increase dramatically as you go from dino, to semisynth to cheap synth to full ester synth. And Brands do make a difference.

This chart can give you an idea, although these are not the ideal oils:

http://micapeak.com/info/oiled.html

(note, for all I know, that could be Amsoil propaganda, I did not get my friends at FBI to look deeply into this matter. I am just posting to show that there are significant differences)

[belfastguzzi]

DL, I think that PR was being facetious, ironic,