Hi, I also have a 05 4.6-3V GT ang have been through all kinds of oils which costed me one cam phasers change, one rocker arm set of 24 and two hydraulic lifters changes. Last update was a set of Ford Racing 24 lifters and 24 rockers.
Tried Fuchs 0-20 - absolutely no standards or approvals, Eneos 0-20 - their middle offering (only available), Amsoil 10-30 and 0-20 (no approvals or standards), Motul 0-20 ester, Yacco something SAE-30 and SAE-40 - looked at the highest SAPS, other Motuls, Agip 10-30. Some kind of 5-40. etcetera. - the higher viscosity, the noisier.
The only of the listed that worked good was the Motul 0-20.
I have the car from 2008-2009, got it with very low mileage, like 10k miles in perfect condition and inflicted all the tapping and other noises only because, firstly and mainly, read BS about thin vs thick oils and the conspiracy of the CAFE and manufacturers to break people's cars once out of warranty and secondly, there were no ILSAC GF-4 API star 5W-20 oils on the market in Europe. It's absolutely absurd why the Americans still bite that hook and go for anything different than ILSAC and API SAE 5W-20 approved oil, either OE Motorcraft or quality synthetic.
Facts:
Roller cam-rocker valvetrain
Motorcycle belt type timing chain (no gear teeth protrusion, thus no shearing forces)
->5.2 bar (75 psi) rated minimum hot oil pressure at 2.000 rpm, otherwise engine check light will come onB]
Highest metallurgical and machining tolerances on that engines
Finest cylinder bore honing adapted to hold low viscosity oil
Friction on top compression ring is semy dry anyway irrespective of what oil you would use
Engine builders have stated numerous times that they found excessive wear in modular 3V engines that were ran with SAE-30, 40 and 50
There are 200k+ mi stock engines happily running on Motorcaft 3k mi oil changes (perfectly adequate having in mind those are group II and III+ hydrocracked)
The switch from SAE 20 to SAE 30 is a swithc from 100C cst of 8.5 to 11 - immediate drop of oil flow by more than 20%, not to mention that there are 12-13 cst@100C SAE-30 oils, which would be cutting the oil flow in half;
At that high oil pressure, imagine what is the cold oil pressure, something like 7-8 bar above idle, you are maxing the oil pump baypass valve, thus confronting the oil filter with excessive pressure, thus forcing it to compress the bottom spring and to also operate in baypass mode, thus allowing any metal shavings and dirt to pass into the oil system;
Metallurgically an engine designed for SAE-20 and 210-214F coolant highway operation is very tight and strict, there is no way a SAE-30 to work properly in hydraulic lifters, they will just work dry and make excessive lash untill they eventually wear out to the point that they start tapping.
What exactly is there to wear out in that engine? crank bearing or con rod bearings? Really?! At 5.2 bar minimum? (75+ psi) No way! Cam bearings (bearingless caps in the head) at that pressure? Only way to damage those bearings is to starve them for oil with "thick" oil and also, to reduce the oil flow to the point that the new thicker oil has so much internal friction and so low flow that it lets the parts overheat around it.
I have a suspicion that even SAE-16, 12 or 10 will work just fine.
There is nothing that can make noise in that engine under normal conditions and there is nothing that can be silenced by oil. Roller cam and belt like chain.
What I discovered a couple of years ago is Ravenol, most of their gold bottle oils are PAO and some are PAO with esters, they use high tech additive pack and have API, ILSAC and manufacturer specific approvals and specifications. Currently running 5W-20 SFE with HTHS of 2.9 which is the highest HTHS I have seen for a SAE-20 oil. Maybe even that high HTHS is undue and causing excessive fuel consumption and power loss. There is another 5W-20 that is compatible and has normal HTHS. Two oil changes, all problems solved, no tapping or noise. Due to 2-3k mi oil changes it has always been bare metal clean and shiny inside.
Bottom line: I really don't see how a moderate cylinder pressure, non flat tappet, non protruding timing chain, fine honed, tight toleranced engine could be damaged or worn out by a quality SAE-20. It is exactly the opposite. A higher viscosity oil would flow less, be shaved off cylinders, starv for oil certain parts of the engine, while overheating them and others, would overload the oil pump and force bypass operation of the oil filter.
Best regards!
and I have few mods that increase power (CAI, exhaust, ecu software)
