Eddie Young uses GTX in all his engines..
https://shop.advanceautoparts.com/p/...hoCjuoQAvD_BwE

maybe thats available in the land of the Fins?

For Amsoil I use COMPETITION DIESEL DOMINATOR 20W-50
https://www.amsoil.com/p/amsoil-domi...gxMzY0OTQ2NjYw

For film strength.
Zinc ≈ 1,200–1,400 ppm; Phosphorus ≈ 1,000–1,200 ppm.

.

For a marine engine with forced induction (turbo or supercharger), especially under heavy loads, here are the specific ways COMPETITION DIESEL DOMINATOR 20W-50 helps — and things you benefit from over a more “standard” oil.
Benefit How DOMINATOR’s Spec Helps / What It Does

Higher film thickness / load-bearing capacity
The oil is formulated to deliver “50% more film thickness” compared to the 3.5 cP HTHS limit of SAE 15W-40. This means during high cylinder pressures (as you get with turbo boost, high torque, etc.), the oil maintains a thicker protective layer between bearing surfaces, pistons, rings, etc., reducing metal-to-metal contact and wear

Better resistance to fuel dilution
In boosted diesels (especially marine), you often get more incomplete combustion, blowby, or fuel entering the crankcase or ring area. That dilutes the oil (thinning it) and reduces protection. With a more robust synthetic base and stronger viscosity maintenance (both at operating temp and under shear), this oil holds its viscosity better even as dilution occurs.

Strong high temperature / turbo charger protection
Turbos get very hot, especially in marine settings where cooling is harder and airflow can be more restricted; oils near the turbo see high heat and need oxidation resistance and deposit control. DOMINATOR’s synthetic formulation with high oxidation inhibitor content helps prevent breakdown, coking, and deposit build-up, helping prolong turbo life.

High HTHS viscosity
With ~5.5 cP HTHS at 150°C, the oil resists thinning under high shear / high temperature better than lower viscosity oils. That helps preserve oil film under load / rpm / boost.

Good cold tolerance (to an extent)
The pour point (-37°C) and the cold cranking simulator numbers indicate it will behave better on cold startups than many heavy non-synthetics. For marine, depending on water temperature or ambient, that helps reduce wear during startup. But note: “20W” means it won’t flow quite as freely as a 15W or lower at very low temps

High TBN & Ash / Detergent / Dispersant capacity
TBN of ~10.1 gives buffer against acidification (from combustion, sulfur, etc.), helping prevent corrosion, soot / ash acidity damage. Good when running hard. The ash content is ~1.0 wt% – trade-off: more ash means more potential for deposits in some applications, but in competition / boosted context that's acceptable.

This oil is very well suited for a boosted marine diesel engine, particularly one used in hard duty / high load / high RPM / turbo conditions. It gives you:

• Strong protection under high pressure and heat
  
• Resistance to breakdown and deposit formation (especially in turbo area)
  
• Better handling of fuel dilution and shear stress
  
• Good buffer against acid and wear
  

My other favorite is Driven MR-50 15w50
I put in a distributer incorrectly and didn`t engage the oil pump.
idles for 10 minutes and I got on plane at 2000 rpm before I saw the warning light didn`t turn off.
Thought the engine would be toast but nothing in the oil filter at all. Ran it rest of the season without any issues.
That`s impressive.

Have used The comma xflow 15w40 mineral For the brake in My new build, and all The Time with My Old engine with The same short block, bearings, melling select 10774/60psi spring, cold Idle 60psi, hot Idle always over 40psi, from fast Cruise to wot 60psi. On The new build i replaced The GM roller lifters For Johnsson 2126bbr with axle oiling, and seems that those bleed some pressure when The oil IS warm, approx 10psi. I also changed merc 8qt oil Pan For 8qt milodon full sump kick Out Pan with all The goodies. IT IS also possible that i Have too much oil in The pan, and that robs pressure.

You mean with too much oil...you're getting the oil entrained into the crank and starving the pump pickup a bit, resulting in 10psi reduced pressure?

If the lifters are bleeding off, the end of the lifter gallery will have even less oil pressure.

Grooves are often cut into the lifter bores for FT cams. It does add to the oil management issue, getting into the crank, just like your new Johnsons will.

My gen6 block IS priority main oiled, If that helps. Mk4 IS difference.

Since you are in Europe, take a look at Ravenol. Good stuff.

Ato24.de has great prices, and I am sure they can ship to Finland. (They ship to Sweden).

I assume you Have big block right? What ravenol you Have Been using?

No big block for me. I am one of those sophisticated outboard cat people.

If you want a load of zinc, I think the Break-in oil is the one to get. You will find specs on the Ravenol website, so you can pick based on what you think your engine needs.

I think my redneck friend with a Pro Charger on a 540 was considering this one:

https://www.ravenol.de/en/product/mo...rfs-sae-15w-50

He got a good deal on some Amsoil, so ended up going with that. More redneck, too.

Very interesting products indeed. What i really like they spec different oil for gasoline and Diesel marine engines.

Of course Priority Main feed...but the same concept on the main priority feed gallery. The end feed port tonthe last bearing will have reduced oil pressure compared to the 1st in line.

Same factor with your bleeding lifters. Less pressure at the end...meaning less than the gauge indicated.

No big deal...it's always been this way. The recomended pressures account for that. The bleeding lifters are the 'new' factor. It drops 10psi across the board. Confirm your pressures/volume is GTG and carry on. Oil flow will also cool the lifters and rollers.

Lucas makes a Hot Rod oil. It's likely destructive with the ultra high level of Zinc...almost touching 3000ppm.

It's had a bad rap for frothing.

Their additive is just a thickener, and displaces additives.

They feel like more of a marketing company vs a perf lubcricant Co.

I wouldn't run it it was free.

https://pqia.org/lucas-hot-rod-classic-sae-10w-40-motor-oil/