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MyMach5 · 02-26-2009, 01:22 PM

I use 10w40 GTX in my 350 as well. I think it works great and I change it about every 2k-3k.

Synthetics are great oils (I use 0w40 Mobil 1 in my track car) but you have to be careful with our older engines. The oil molecule in a synthetic is smaller than a conventional. If you have small oil leaks now they will only get worse with the Synthetic. You may also start leaking oil with the Synthetic where you didn't have leaks before.

02-26-2009, 01:22 PM	#6
MyMach5 Registered User Join Date: Jan 2009 Location: Portland, OR Posts: 44	Re: Recommended Oil for a factory 350? I use 10w40 GTX in my 350 as well. I think it works great and I change it about every 2k-3k. Synthetics are great oils (I use 0w40 Mobil 1 in my track car) but you have to be careful with our older engines. The oil molecule in a synthetic is smaller than a conventional. If you have small oil leaks now they will only get worse with the Synthetic. You may also start leaking oil with the Synthetic where you didn't have leaks before.