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Oil recommendation for 70 Monte.


wtd

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My 70 Monte has a 396 BB in it and I've been reading lately about how the newer SM and SN oils don't have enough zinc in them anymore to protect the flat tappet cams in these older engines.

 

What brand of oil are you guys running in your older engines and are you worrying about the lack of zinc in these newer oils.

 

Some people are telling me to run a HDEO oil made for diesels but I've been reading that even these have had thier zinc levels lowered. Thanks for any ideas or input.

 

I'm currently running valvoline 10W-40 which I added Lucas zinc-plus to but I don't know if this is the best option.

 

Wayne

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Used to run the 50\50 fossil, synthetic in my 02 Silverado.

Then did some research. Found out the supposed benefits did not out weigh the additional cost. Go full syn. or fossil.

 

Regarding a good oil for the older engines. I know there are several manufacturers out there now producing specialized oil for high mileage or older engines.

Thinking one of them should do well for your application.

 

If it were a new\fresh build I would not hesitate suggesting full synthetic. But have heard of seeping\leaking problems when used on older engines due to thinner viscosity.

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This has been written about and discussed many times on this forum and others. If you are not racing or towing and you have a flat tappet setup, I think it is safe to say pick any brand of 10W-30 oil you like or trust, either synthetic or not and add ZDDP to it.

 

I use Mobil 1 full synthetic with ZDDP and I've not had a problem in the past 6 years with this combo.

 

Mike

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A 10W-30 oil is pretty much out for me because my oil pressure runs too low on it and is why I use a 10W-40 and what I've pretty much ran in this car since I've owned it.

 

I won't use Mobil 1(that is for another thread) so that is out. I'm considering Amsoil as an option or some people have suggested to me to run oil from like John Deere.

 

I've got the lucas additive in this oil change and see how that goes.

 

Wayne

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I'm running Rotella 15-40 with a bottle of ZDDP in my all original 97K mile 402BB. I only plan to change the oil twice a year at the beginning and end of the cruise season.

 

Been running this same combo in other flat tappet motors for years without an issue. The important additive is the bottle of ZDDP. I would guess that any oil would work fine as long as that additive was in it.

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It is understandable to choose between synthetic and non but as long at the weight is the same the viscosity should be the same as well. the 10w-30 is the viscosity rating that applies to both types of oil and they will flow the same under the same conditions UNLESS you are talking sub-zero temperatures. Then you will notice a difference in oil pressures on startup. While the dino oil will seem to have higher pressures, that is due to its resistance to flow while cold and you could run into lack of oiling. Synthetic oils flow closer to their respective rating over a larger range of temperatures.

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....the 10w-30 is the viscosity rating that applies to both types of oil and they will flow the same under the same conditions.....

 

By no means am I attempting to debate. Am very weak when it come`s to the in`s and out`s of oil speak. blush

Just trying to learn and understand.

Just have seen on many an occasion as well as a personal experience and heard the same from several Mechanics.

 

The leaks after changing to synthetic may have been purely coincidental, would have happened even if fossil had been used.

But they did happen, in more then one case, on multiple types of vehicles. confused

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Either Amsoil, or Royal Purple 10w40 will do the trick. Both have a type with a high zinc content. I've used both and get the same results. I only change my oil once a year as I'm lucky if I put 2,000 miles on my Monte. For my daily drivers I use Valvoline full synthetic(one truck and one car) and change the oil between 4-5,000 miles. Don't car much for what folks say about oil change intervals. I'll do mine and they can do theirs as they like, plus it's my money anyway. Hope that helps.

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This is not an option anymore, but several years back when I read that Rotella T 15W40 SL rated oil was going to be replaced with the SM version that severely reduced the zinc content, I purchased 240 gallons of the SL oil before it became extinct. I also purchased 50 gallons of the SL rated Rotella Synthetic 5W40. I've been using these two oils ever since in all my oldie goldie cars as well as my lawn equipment. My 67 VW Beetle has 150k miles on it with the old Rotella T and I swear she still does not burn a drop of oil (I hope I didn't just jinx muyself). When I eventually run out of Rotella I'll use Brad Penn oil which I can buy locally.

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For this oil change I'll stick with the Valvoline 10W-40 and the Lucas ZDDP and than decide what to do from there. I just don't want to ruin the engine before its time. Thanks for all of the input.

 

Wayne

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Is the zinc additive required in the GM 350 crate motor since it was built based on the 80 model engines?

 

If the motor has a flat tappet cam then Yes it requires ZDDP additive. Roller cam motors do not require it but it doesn't hurt anything wither

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