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LIQUI MOLY 5W40 lab analysis after 4,000 miles in a 2004 V11 with 35k miles total.


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3 hours ago, audiomick said:

Ok, overkill. I hear what you're saying, but I'm interested in knowing if it is bad for the motor in any way. Going by what you have said, regular oil changes are important. Are there any other disadvantages apart from the cost of th oil?

Regarding stressed valve gear, that is an issue with the small block motors too. The 2 valve motors aren't that critical. Particularly the Breva 750 is not particularly affected, as the later models had single valve springs that didn't give the valves such a hard time. The earlier ones, like the V35 II motor in the Imola, had double valve springs that were too hard, and the valve gear is highly stressed as a result. They need a fairly high viscosity oil.

Particularly the 4-valve small blocks had chronic valve problems. My Imola has a 2 valve motor, but I have most of a 4-valve motor sitting on the shelf, and maybe one day I will put it together and bolt it into the Imola. :)

The cost of the oil is the main thing and the fact it will shear down faster and absorb more engine power. Also bear in mind that higher viscosities also means reduced oil flow through the engine bearings and therefore less cooling for the bearings. What you want is the lowest grade oil you can run for cold starts and the lowest grade for normal operating conditions with some "headroom" for times when the engine is run hard such as flogged up a mountain pass or a track day or a high speed Autobahn run on a hot day. I remember years ago I read about a mod to the SB 4 valvers using Suzuki valves and springs was it? I also recall the main issue was the cam design in those engines as the reason they dropped valves.

ZDDP is Zink Dialkyl Dithiophosphate a sacrificial anti wear additive that basically bonds to areas inside the engine under extreme pressure and acts as a sacrificial boundary layer if the oil film is compromised. So the lifter face to cam lobe interface on a flat tappet engine is a prime example. Interestingly too much ZDDP actually causes greater engine wear.  PPM is parts per million. Zink levels have been gradually lowered over the years due to catalytic converter issues and the fact most modern engines don't use flap tappet lifters and have 4 valve heads without the heavy valve seat pressures of past years. 

Phil

Edited by Lucky Phil
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7 hours ago, Lucky Phil said:

...What you want is the lowest grade oil you can run for cold starts and the lowest grade for normal operating conditions with some "headroom"...

Thanks, Phil. That's the sort of information I am always looking for.

I do tend to stick to the specification in the manual, not only for oil, but like to know the background and what potentially might happen if one deviates from the spec. .:)

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On 8/8/2024 at 5:36 AM, motortouring said:

I heard something about these low-viscosity oils having a better performance on the emissions. Since a part of the emission tests is with a relative cold engine the 0Wxx or 5Wxx have less resistance than the 10W. 

Yes, l found a Toyota diesel got better range on 5W-30 oil than 10W-30. The manual allowed both. The local Toyota service center used 10W-30 Castrol on my Hilux, and when I changed the oil myself using 5W-30 Penrite, I found that I got an additional 100km range per tank.

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19 hours ago, pete roper said:

What are the three functions oil performs?

Lubrication, heat dispersal and detergent action of combustion by-products?

 

Edited by po18guy
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2 hours ago, po18guy said:

Lubrication, heat dispersal and detergent action of combustion by-products?

 

 

34 minutes ago, audiomick said:

You're right, according to Pete, but Phil has already collected the elephant stamp. :)

 

With @po18guy's definitive wording, I say he's eligible for the Silver Elephant Stamp. :grin:

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More to the topic, I had always thought (no experience) that oil analysis is used to establish change intervals, especially on industrial and commercial equipment with very large capacities (gallons). Or optimizing oil change intervals over a fleet (drums) . . . ?

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1 hour ago, docc said:

More to the topic, I had always thought (no experience) that oil analysis is used to establish change intervals, especially on industrial and commercial equipment with very large capacities (gallons). Or optimizing oil change intervals over a fleet (drums) . . . ?

Yes docc good point I would assume they use UOA for that as well to save money with semi's etc in large fleets. In these large trucking fleet  companies I know they have dedicated departments that do nothing but monitor the trucks mechanicals in real time as they are on the road. I would assume they use UAO for plotting their oil changes as well. I guess it depends on the engines oil consumption. Engines that are used commercially and are running 24/7 obviously consume oil and it gets to a point where you no longer need to do oil changes because the consumption and top offs are cycling the oil through anyway. Big gas turbines are like this. Because they burn around a quart/hour you never change the oil like a bike or car, there is no point as fresh oil is always being installed. I remember when I started in aviation and some of the old guys had tons of experience on big radials they talked about how pointless and annoying it was doing a mandated oil change on the bloody things because they consumed so much it was a pointless exercise dumping 25 gallons of oil that was in reality never that many hours old.

The old Lockheed Super Connie Qantas used to fly had a dedicated oil tank and engine replenishing system in the fueslarge that the flight engineer used to pump fresh oil to each engine on long flights to keep the main engine oil tanks at a safe level they used so much.

Phil 

Edited by Lucky Phil
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Credit to Kevin Cameron for accumulated tech knowledge.

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