Been using Castrol GTX 10w30 for a year in my new a year ago Goodwrench 350 flat tappet engine. Had to get some front diff work on the Suburban yesterday and the topic of ZDDP came up and the mechanic said I had already ruined the engine by using Castrol GTX without adding a ZDDP supplement. So I asked him why does GM warranty my new Goodwrench 350 flat tappet engine for 36 months or 100,000 miles if the current oils are "deficient" in ZDDP? He didn't say much after that. Was he right or embarrased.
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Conventional oils(10w30)
- Thread starter MojaveK20
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In my opinion he is wrong... as long as you dont run a 5w30. but I better step back and let some others weigh in
Both you and your mechanic are making this an all or nothing argument, but it's not one.
It's very possible that because of the low-zddp oil there is more wear on either the tappets or the cams. More wear isn't the same as ruined. But I doubt that's the case and I wonder if they aren't rollers anyways?
It's very possible that because of the low-zddp oil there is more wear on either the tappets or the cams. More wear isn't the same as ruined. But I doubt that's the case and I wonder if they aren't rollers anyways?
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Getcha some Valvoline VR1 street oil.
This question reveals a dilemma for suppliers of replacement engines for older cars. They are going to have to make very specific oil recommendations for flat tappet replacement engines. Most do not have high spring pressures or fast opening cams so the problem may not be very big. Does GM offer any flat tappet performance engines?
The main issue is during break in. Did they recommend using EOS during break in? Using supplements during flat tappet break in is probably mandatory with today's oils.
The main issue is during break in. Did they recommend using EOS during break in? Using supplements during flat tappet break in is probably mandatory with today's oils.
I just looked, and all the higher HP GM Performance Parts crate engines have roller cams. But the low hp 350s have flat tappet cams!
MojaveK20
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Originally Posted By: ledslinger
This question reveals a dilemma for suppliers of replacement engines for older cars. They are going to have to make very specific oil recommendations for flat tappet replacement engines. Most do not have high spring pressures or fast opening cams so the problem may not be very big. Does GM offer any flat tappet performance engines?
The main issue is during break in. Did they recommend using EOS during break in? Using supplements during flat tappet break in is probably mandatory with today's oils.
The shop that replaced my engine(different from the one I was at yesterday) used EOS and had me change the oil and filter after 500 miles. He said any conventional 10w30 was just fine after that since I change oil at 3000 due to 120+ temps here and the dust.
This question reveals a dilemma for suppliers of replacement engines for older cars. They are going to have to make very specific oil recommendations for flat tappet replacement engines. Most do not have high spring pressures or fast opening cams so the problem may not be very big. Does GM offer any flat tappet performance engines?
The main issue is during break in. Did they recommend using EOS during break in? Using supplements during flat tappet break in is probably mandatory with today's oils.
The shop that replaced my engine(different from the one I was at yesterday) used EOS and had me change the oil and filter after 500 miles. He said any conventional 10w30 was just fine after that since I change oil at 3000 due to 120+ temps here and the dust.
Quote:
But the low hp 350s have flat tappet cams!
My brother had one of the "Target" engines that ate a cam some years ago. I dunno all the details, but he didn't get a replacement, he had to take care of it himself. He'd been using 5-30 or something in there, after the cam/lifter change, he went to Rotella T Synthetic 5w40. He sold the truck to a local guy - last I heard, several thousand miles later it was working fine.
I'm guessing something like Rotella 10-30 would also be a good choice.
But the low hp 350s have flat tappet cams!
My brother had one of the "Target" engines that ate a cam some years ago. I dunno all the details, but he didn't get a replacement, he had to take care of it himself. He'd been using 5-30 or something in there, after the cam/lifter change, he went to Rotella T Synthetic 5w40. He sold the truck to a local guy - last I heard, several thousand miles later it was working fine.
I'm guessing something like Rotella 10-30 would also be a good choice.
I assume it is the GM engine (260hp) service replacement engine, because that and the GMPP 350 H.O. are (and I could be wrong) the only replacement small block engines GM installs flat tappet hydralic cams in.
But I think the shop that performed the install, according to your details, gave you the correct information. Here's my reasoning: 1) The valve springs in the 76cc 1.94 heads are pretty week, that is, they are somewhere in the neighborhood of 80lbs on the seat and maybe 260lbs. open. From all my research and trials, any valve spring pressure under 100lbs. on the seat and 300lbs. open will permit any SM type oil without any Z & P additive. 2) As we all know, the critical time is during break in and the mechanic did add GM EOS to the oil at initial start up.
If you are questioning your engines need for more Z & P, find some diesel or VR1 or anything else which supplies more Z & P per million. Otherwise if nothings broke, keep doing what you are doing.
But I think the shop that performed the install, according to your details, gave you the correct information. Here's my reasoning: 1) The valve springs in the 76cc 1.94 heads are pretty week, that is, they are somewhere in the neighborhood of 80lbs on the seat and maybe 260lbs. open. From all my research and trials, any valve spring pressure under 100lbs. on the seat and 300lbs. open will permit any SM type oil without any Z & P additive. 2) As we all know, the critical time is during break in and the mechanic did add GM EOS to the oil at initial start up.
If you are questioning your engines need for more Z & P, find some diesel or VR1 or anything else which supplies more Z & P per million. Otherwise if nothings broke, keep doing what you are doing.
Use 10w30 diesel engine oil. That will do a fine job and ease your mind. It might be hard to find, so plan ahead. These oils are dual-rated for both diesel and gasoline engines, so no worries.
Here are the Chevron and Shell data sheets, but use any top brand.
https://www.cbest.chevron.com/generated/MSDS/PDS31613214.PDF
http://www.shellusserver.com/products/pdf/RotellaTCI-4CI-4.pdf
Here are the Chevron and Shell data sheets, but use any top brand.
https://www.cbest.chevron.com/generated/MSDS/PDS31613214.PDF
http://www.shellusserver.com/products/pdf/RotellaTCI-4CI-4.pdf
First of all...that stock replacement 350 doesn't have a high enough valve spring pressure to cause severe wear with an SM oil (in my opinion).
Second of all, my flat-tappet '01 4.0L Jeep (and millions like it) run fine on SM rated modern conventional oils...again, not HP so not a concern.
If it was mine, then yes, I'd probably run Mystik 10w30 or something with more ZDDP since it is a suburban and probably tows & stuff, and it is flat tappet....but as said above...it is not runied & the good news, the break in process is over so it really doesn't matter as much now; but u could switch to something else anytime...I doubt you need to run a 15w40 or something that thick...I would stick to 10w30 for most climates or 10w40 if it is real hot or towing heavy loads. Heck, a High Mileage oil like Pennzoil High Mileage might have more ZDDP and maybe you could use that.
Second of all, my flat-tappet '01 4.0L Jeep (and millions like it) run fine on SM rated modern conventional oils...again, not HP so not a concern.
If it was mine, then yes, I'd probably run Mystik 10w30 or something with more ZDDP since it is a suburban and probably tows & stuff, and it is flat tappet....but as said above...it is not runied & the good news, the break in process is over so it really doesn't matter as much now; but u could switch to something else anytime...I doubt you need to run a 15w40 or something that thick...I would stick to 10w30 for most climates or 10w40 if it is real hot or towing heavy loads. Heck, a High Mileage oil like Pennzoil High Mileage might have more ZDDP and maybe you could use that.
It is the break in that is important with that engine.
This has long been accomplished.
It is a mild street engine with an old fashioned but pretty durable valvetrain.
This has long been accomplished.
It is a mild street engine with an old fashioned but pretty durable valvetrain.
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