opinions...Castrol syntec 10w-40, Pennzoil High mileage 10w-40

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May 9, 2003
Fayetteville, NC

Some of you might remember my recent oil consumption problem with switching to synthetic (pennzoil 10w 30) from non-syn. oil(Pennz. HM 10w-40).

So, I'd like to try a heavier oil in my T-bird'd 4.6l v8 modular motor (85,000 miles). I want to get a good oil that's not TOO heavy for this motor, and an oil which is availble at a normal store, not mail-order oil.

So far I've considered:
A) Castrol syntec 10w-40 (a little scared of this one 'cause it's synthetic, which might damage my old seals/cause them to leak more?? but I've heard it's good; A3 and all that..)
B) (back to) Pennzoil High Mileage 10W-40

C) Motorcraft 10w-40 (regular)

I've used both B and C with ok/good results.
What do you think? which is better suited for my purpose? Pls help, I really need to make this decision soon...Thanks a lot in advance.

(if it helps your feedback: I live in Tenessee, drive ca. 50 miles a day, use Motorcraft FL-820S filter, change oil every 3K miles.)

Castrol Syntec 10w40 is not PAO based, so you shouldn't have any issues with seals. It's mostly a group 3 oil, possibly with some esters mixed in (nobody knows 100% for sure, but speculation is that the US made Syntec is part group 3 and part esters)
I am now runing Motorcraft 10w-40 in my truck with nice results. I will be doing a uoa in a few weeks to see if the oil is doing any shearing. That is my main concern with the 10w-40 is the high content of VI improvers. You may want to play it safe and go with the Penz. high mileage in the 10w-30 weight. It has a nice additive package with a nice dose of moly.
If you're having consumption problems I'd suggest that you try Quaker State's high mileage 10W-40. It seems to be the thickest of the 10W-40 oils.

How did the Pennzoil High Mileage 10/40 work for you?

oil consumption was half a quart per 2,600 miles. I bought the car used with 72,000 miles. Previous owner said he always used Pennzoil 10w/40
If you have a '97 T Bird with the 4.6L I don't think I'd be using an oil with a 40W in it. I believe that it's just too thick an oil for this engine. Did you own this vehicle from new and if so what oil did you use. If you bought it used do you know the maintenance history. Perhaps a treatment with Auto RX first might help with your oil consumption. By the way how much oil are you using per mileage. Unfortunately some engines just use a certain amount oil from even day one.

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