Best over the counter oil for 1994 stock 350 tbi flat tappet

In my 94 with a edelbrock 3702 flat tappet cam I run Castrol GTX conventional, and use lucas zinc additive. Haven't had a problem yet.

My late father got me started using Quaker State straight 30 weight in our square body trucks with 350s, then when we got our first 99 Burb with the vortec 350 he went to QS 10w30 as that's what was recommended in the owners manual. That truck went for 255,000 miles with no oil related issues. When l did the timing job and had the pan off at around 180,000 the crosshatch in the cylinder bores was still in very good condition. The 99 vortec 350 Burb l have now just made 175,000 on a trip to Louisiana over the weekend, and I use QS high mileage red label 10w30 in it. No leaks or rattles and l change it around 4000 miles. Truck runs so smooth and quiet that you have to put your hand on the door to be sure it's running if you can't see the tach.
Anyway that's just my 2 cents, good luck with whatever you choose. The kind l use l get at Walmart, 5 quart jug is around $16, single quart is about $5.

I've been running Mobil1 10w-40 or even 0w-40 (same as in my Chyrysler Crossfire) in my Mexican GM Goodwrench 5.7L since it was new in 2002 and still doesn't leak or burn oil. I recently redid the top end with aluminum heads, bigger intake and flat tappet cam. Broke it in with regular 5w-40 and ZDDP aditive for 20 minutes @2000 - 2400RPM, changed the oil with the same stuff for another 500 miles and went back to Mobil1. Be careful with diesel oils, they do have higher zinc and will plug your cat eventually.

454cid said:

I think most of you guys are missing the important part here.... Flat tappet cam. I've read over and over, that modern oils are tailored for roller cams.

I would probably run Rotella T4, as I believe it's got the higher zinc levels needed. Technically it's not gas engine rated any more. When the new ratings came out Shell didn't certify it for gas engines... not sure why, the other HD oils from other companies got dual rated.

The T4 is available in 10w30, so you can run the HD oil without going to a viscosity that's too heavy.

You could check over at BITOG, all they do is argue about oil. Someone's probably already asked the question.

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man-a-fre said:

What brand and weight are you guys using for oil in your flat tappet motors?. I just finished breaking in my new mexico GM 350 and am now looking for easy to get oil that will work and keep the cam alive and is carried at the usual chain stores.

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As

As far as I know, no "over the counter oils, conventional or synthetic, contain 'zink' which is the oil additive that would help protect the lobes and lifters of your flat tappet cam.
The best solution is to use the oil you prefer and add a 'zink additive'.
ZINC OIL ADDITIVE 2 oz. BOTTLE

ZINC (ZDDP) is widely known to be the prime ingredient to protect flat tappet cams and valve train components within engines using heavy increases in valve spring pressure, to control aggressive camshaft profiles. ZINC is also the protective additive necessary to protect older vintage engines that were produced when Zinc was the prime additive used to provide the last measure of protection against catastrophic failure. It is necessary for the proper amount of ZINC to be used in relation to engine oil for the ideal amount of protection. Zinc provides the proper amount of the ZDDP additive to treat six quarts of engine oil, giving the proper ratio of 3000-3200 ppm for proper engine break in and protection of high pressure valve train components. It is important to understand that ZINC is blended with a light base mineral oil that aids in the quick and complete dispersion into any engine oil for fast activation and protection during first startup. For maximum protection ZINC must be reapplied to engine oil when the oil and filter are changed.

PlayingWithTBI said:

Be careful with diesel oils, they do have higher zinc and will plug your cat eventually.

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We've had cats much longer than they've been removing the zinc, from oil... besides most of them aren't "diesel oils". They're HD oils and are dual rated for diesel and gas.

Here's a clipping from Amsoil discussing what high ZDDP does to cats and why it's needed with flat tappet cams. It also says synthetic oils work for reduced friction.

https://www.amsoil.com/newsstand/classic-and-vintage/articles/reduced-zddp-and-wear-protection/

What's a ZINK? I haven't seen it spelled that way.

Kodiak said:

As far as I know, no "over the counter oils, conventional or synthetic, contain 'zink' which is the oil additive that would help protect the lobes and lifters of your flat tappet cam.

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