Oil - Type to use and best

[G.T.]

My alternate to OE-spec for most any vehicle is any euro oil with MB 229.5 and/or BMW LL01 approvals. Plenty stout and easy to find almost anywhere.

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[bKennedy]

re: VCT being "designed" for 5W20

Don't a lot of people point to the thicker oil recommendation for track use as the thinner oil doesn't work the VCT as well?

I'm no exert on cam phasers but I remember reading, or seeing, that using a thicker oil may affect them negatively as oil pressure operates them. I think the owners manual says that you can use 5W-30 if you are going to race the car but at the next oil change go back to 5W-20. I think that the heaver weight oil just protects the engine better at prolonged high speeds and engine temperature. Many car companies recommend a thinner weigh oil in the US but in other countries recommend a heavier weight, why is that? It's to meet the CAFE (Corporate Average Fuel Economy) standards at the detriment to the engine. Everyone has to make their own decision on what viscosity oil to run, I feel good about 5W-30 since I live in NC where the temperatures are always relatively mild in the winter. When I lived in Minnesota 5W-20 was fine in the winter months. Due to oil shear oil in the car starts loosing its viscosity over time, I prefer to start out with a little higher viscosity as 5W-20 seems a little thin to me to start off with.

 

[robvas]

I'm no exert on cam phasers but I remember reading, or seeing, that using a thicker oil may affect them negatively as oil pressure operates them.

You have it backwards. They work off oil pressure so they need a thicker oil to ensure proper operation at higher RPM, high oil temperatures, etc that you see on the track.

 

[bKennedy]

You have it backwards. They work off oil pressure so they need a thicker oil to ensure proper operation at higher RPM, high oil temperatures, etc that you see on the track.

I usually want to be correct when I make a statement and I remember reading that too thick an oil cannot get through the small passages in the cam phaser so I went online and checked it out, the answer I got is below. In addition if the oil pressure is higher than what the Engine Control Unit (ECU) wants to send to the phasers it will instruct Oil Control Solenoids to limit the pressure going to the phasers so having excessive oil pressure will not do you any good. As long as you have enough oil pressure a thicker viscosity will not help and may hurt when it comes to getting into the small passages it needs to flow into. Now on the track I agree that you should use thicker oil in some cars especially if they are designed for racing and have looser tolerances to allow more oil into rod and main bearings. However we are talking track use and perhaps you should also have a better oil pump than what comes in our stock engines to keep the oil flow and pressure where it need to be for extended track us. I would say the vast majority of us never track our cars and probably shouldn't use more than a 5W-30 oil unless you live somewhere that has very high daily temperatures; Las Vegas, Phoenix, etc. Thicker oil is not going to help your cam phasers work better, correct oil pressure will.

Yes, using oil that is too thick (higher viscosity) can absolutely cause incorrect cam phaser operation by slowing down oil flow, preventing the phasers from reacting quickly enough to adjust timing, leading to rough idling, check engine lights, and potential engine damage over time. Thicker oil creates more resistance in the narrow passages feeding the Variable Valve Timing (VVT) system, reducing oil pressure and flow to the phasers, which are hydraulically controlled.

 

[robvas]

Yes, using oil that is too thick (higher viscosity) can absolutely cause incorrect cam phaser operation by slowing down oil flow, preventing the phasers from reacting quickly enough to adjust timing, leading to rough idling, check engine lights, and potential engine damage over time. Thicker oil creates more resistance in the narrow passages feeding the Variable Valve Timing (VVT) system, reducing oil pressure and flow to the phasers, which are hydraulically controlled.

Never heard of 50 weight causing check engine lights on these cars. Or clogging oil passages.

The gen 2+ phasers don't rely on oil pressure in the same way as the earlier ones, there is a video from the manufacturer explaining how they work. The first gens were different. But even then the vct calibration tables were the same on track pack and non-track pack cars (not sure if they were different on the Boss 302 cars)

 

[robvas]

I usually want to be correct when I make a statement and I remember reading that too thick an oil cannot get through the small passages in the cam phaser

Here's the actual snippet about thicker oil that I was looking for earlier. This is from the Boss 302 supplemental owners guide, the VCT calibration in the computer is slightly different than the regular cars, but the point still stands. And the newer cars it shouldn't matter as much.

 

[Supersolo]

Motul 5w30, WSS-M2C934-B, changed evey 5k miles.

 

[robvas]

Restore and Protect didn't clean this engine much

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