Good information. I found some more information on the functioning of the VCT phaser from Motorcraft. The following is what I found,
The basics of VCT operation are:
• A hydraulic timing mechanism (VCT phaser) rotates the camshafts in relation to their drive sprockets.
– Provides performance that is precisely tailored to the engine speed and load.
– VCT is electronically controlled (PCM duty cycled) and hydraulically operated.
• The VCT solenoid moves a spool valve to control the flow of oil through the VCT system.
– Oil flows from the head into the VCT valve body.
– Oil flows through the advance or retard passages as directed by the spool valve.
• Oil flows through the VCT valve body:
– To the chain tensioner.
– Through a metered orifice back into the head.
• Major sensor inputs:
– CMP
– Oil temperature sensor
The VCT system uses a replaceable oil temperature sensor, located on the oil pan.
• Engine oil temperature has a direct effect on VCT operation.
– Cold engine oil has high viscosity and slower flow characteristics.
– The VCT system is disabled at oil temperatures below -7°C (18°F).
– The PCM uses time-since-start, engine oil temperature and engine rpm to calculate VCT solenoid operation.
– Time-since-start ranges from 60 seconds when cold to 10 seconds when hot.
• Engine oil recommended drain intervals must be followed to ensure integrity of VCT system.
3-10
Also saw many pictures of the VCT that have "metered orifices".
So I would say the VCT modulars should be run on 5w20.
The basics of VCT operation are:
• A hydraulic timing mechanism (VCT phaser) rotates the camshafts in relation to their drive sprockets.
– Provides performance that is precisely tailored to the engine speed and load.
– VCT is electronically controlled (PCM duty cycled) and hydraulically operated.
• The VCT solenoid moves a spool valve to control the flow of oil through the VCT system.
– Oil flows from the head into the VCT valve body.
– Oil flows through the advance or retard passages as directed by the spool valve.
• Oil flows through the VCT valve body:
– To the chain tensioner.
– Through a metered orifice back into the head.
• Major sensor inputs:
– CMP
– Oil temperature sensor
The VCT system uses a replaceable oil temperature sensor, located on the oil pan.
• Engine oil temperature has a direct effect on VCT operation.
– Cold engine oil has high viscosity and slower flow characteristics.
– The VCT system is disabled at oil temperatures below -7°C (18°F).
– The PCM uses time-since-start, engine oil temperature and engine rpm to calculate VCT solenoid operation.
– Time-since-start ranges from 60 seconds when cold to 10 seconds when hot.
• Engine oil recommended drain intervals must be followed to ensure integrity of VCT system.
3-10
Also saw many pictures of the VCT that have "metered orifices".
So I would say the VCT modulars should be run on 5w20.