diamonbird

To be called Synthetic Blend it only has to have 10% synthetic oil in it.
Maybe that's enough for you but not me. $63 now or $5000 later.

Mod (Ret.)

Oil wars, yet again.

If you use plain based, or synthetic blend oils, change the oil every 3000 to 3500 miles. Use full synthetic oil and change oil every 5000 to 6000 miles, depending on your driving habits and the oil manufacturers recomendations.

If you use full synthetic and change every 3000 miles, you're wasting your money.

I go back and forth; if synthetic's on sale when my truck requires an oil change, I buy it. If not, I go with synthetic blends and run it for 3000 miles. My engines have been very happy; my 1984 VW Westfalia has over 256,000 miles on it's original engine. My 2000 Harley is on it's second engine; the first gave me 110,000, the second has 36,000 on it. I've been using synthetic blends and full synthetics in all of them. My 2005 4.2 V6 has 88,000 on it with the same routine.

If your really into engine oil efficiancy, install an engine oil cooler. I have one on my truck along with an oil temp guage. Jeggs has them. Lowers your engine oil by about 20 degrees on the hot days.

BISCUT

According to what I've read on BobIstheOilGuy forms they claim MotorCraft 5-20 is about 60% synthetic.

Just repeating what I've read. I couldn't back it up with any testing so take it for what it's worth.