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Discussion Starter #1
I am sure there have been a million oil questions here but I am curious as to what the best oil is for a 4.3L engine. I know that certain vehicles seem to prefer a certain type of oil. For example, I also own a 1994 Geo Metro which was spec'ed with 5W30 dino oil. They didn't have all the synthetics way back when these little cars were designed but people have found that 0W30 and 0W40 oils seems to work really well in these hot running little engines. The ACEA European spec oils for BMW, Audi, Mercedes, etc. are HIGHLY suggested by anyone who works on these little engines. I am actually running a Mobil 1 0W40 European formula as I can usually find this locally and it is usually included in sales for other M1 products so it is pretty cheap compared to the rest of the oils in this class.

Now I know that these are two completely different engines but was wondering if anyone here had come up with any oils that might be the sweet spot for a 4.3L. Also, how good or bad of an idea is it to use a 0W40 or 5W40 vs. the original 5W30 in these engines? I pretty much run synthetics in anything I own and was considering running the 0W40 in all vehicles if that was OK.

Thank you,

Conor
 

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redneck extraordinaire
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Use what chevy calls for in it. That'll be your best bet.
 

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I have a 2000 4.3. You don't need 10W-30 unless you have lifter noise or you live in a very hot climate. You will be more than perfect running a good synthetic 5W-30 in yours (5W-30 is spec'd in the owner's manual and printed on the oil fill cap). I run Mobil 1 Extended Performance 5W-30 in mine and it doesn't burn a drop. I go 5,000 miles between oil changes as well.

But also remember, an oil is only as good as the filter you use as well. Make sure you use a good filter like a Wix, Purolator PureOne, Mobil 1, K&N, etc.
 

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Discussion Starter #6
Yeah, I sometimes get minor lifter noise on my engine but it seems to come and go. I posted once about this a while back and was told this is pretty much normal and nothing that will do harm to the engine.

I guess our engines are not anything that is really hard on the oil or makes sludge like some engines out there. Although I know the GM Dexos spec is new compared to our engines, is this a good way to go as for oil?

I often run Wix or Mobil 1 filters as well as Bosch in the black box. These tend to be included in oil change sales so I end up with them. Are they any good or not? I know just about anything is better than the basic orange Fram.

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I sold the original engine out of my 94 S10 last summer for $100. The engine was all original, nothing was ever changed on it. I purchased the truck at 234k miles. I sold the engine at 298k miles. No leaks, ticks, knocks, or any blow by or oil burning. I used Valvoline High Mileage 5w-30. My new 4.3 build I just did is using Shell Rotella T 15w-40. It depends on your driving, and the application.

Every day driving I'd stick with;
Mobile 1, 5w-30
Valvoline, 5w-30

The biggest thing is looking for the seal on the back of the manufactures carton saying it meets standards and weights. I'd use a synthetic, at minimum a synthetic blend (mixing 1qt synth and 1qt conventional does not constitute as a synth blend). And please, DO NOT mix weights! I've seen people do this, I have yet to see a bad outcome from it, but I don't even know WHY you would do this! And personally I use Valvoline, because the inside of the engine when I sold it, looked practically new! I probably have the pictures somewhere.
 

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"factory freak"...
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Theres nothing wrong with mixing different weights of oil. Ive done it many times
over the years, either out of necessity, convenience , or to achieve a desired weight.
 

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I use Valvoline 5W-30 Conventional motor oil and a Melling Select 10552 high volume oil pump. The low viscosity oil reduces HV pumping losses. I change the oil and WIX filter every 1000 miles with no additives or snake oil.

The NASCAR Sprint Cup and Nationwide Series teams use 0W-5 conventional motor oil. The Cup engines have a dry sump, high volume oiling system with special engine blocks made of nodular compressed cast iron and a oil storage tank in which the oil cools somewhat. The Cup cars have their oil changed every 499 miles at Talladega.
 

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Discussion Starter #10
I will likely just stick with a full synthetic oil meeting the GM Dexos1 or better spec in 5W30. Would there be any harm in a good 0W40 or 5W40 in hot weather? I understand the Mobil 1 0W40 is tested in such a way that the high number would normally be more like a 35W instead of a 40W. The Mobil 1 0W40 meets all the European specs for extended change intervals and cleanliness of the engine internals plus it can be used in some diesel engines. I realize that the entire engine and filtration system must be designed around the extended change interval so I wouldn't be able to take advantage of that.

The reason I ask is that this Mobil 1 is VERY good oil and the 0W40 is usually not differentiated from the 5W30 in price when it goes on sale.

Now as for the racing oil, I don't consider that to be a fair comparison at all. They are likely using such a thin oil to get the maximum amount of power out of the engine. Also, when you have got all kinds of money from advertising endorsements, you don't care about spending a couple tens of thousands of dollars rebuilding an engine after every race or two.

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Low viscosity oil is free horsepower no matter where you are driving. The technology of oil refining has advanced so much today that we don't need thick oil anymore. Twenty years ago, I would never have dreamed I would be using 5W-30 All Season motor oil in a high performance engine. .

A high volume oil pump requires that you use low viscosity oil. Those oil pumps did not exist twenty years ago.
 

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Discussion Starter #12
True! It is free horsepower and free improvement in gas mileage. While some may claim that you should use just what the manufacturer calls for, others say that improvements in lubricants have changed things quite a bit and that is why I am asking. I figure something line a 0W40 gives you the best of both worlds in protection and fuel economy at both high and low temps. It brands like BMW and Mercedes approve, it cannot be crap oil. I understand that ANY oil that meets all the Euro specs is really good stuff! How about oil like 5W20 or 0W20? While it will give better economy, I wouldn't want to destroy my engine for a few cents in gas savings per gallon. While the oils have improved, our engines are designed and built around old tolerances.

As one popular oil brand advertises, it is "liquid engineering" and I agree!

Conor



Low viscosity oil is free horsepower no matter where you are driving. The technology of oil refining has advanced so much today that we don't need thick oil anymore. Twenty years ago, I would never have dreamed I would be using 5W-30 All Season motor oil in a high performance engine. .

A high volume oil pump requires that you use low viscosity oil. Those oil pumps did not exist twenty years ago.
 

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I don't see why using 0w40 Mobil1 would cause you any trouble, the 4.3 is a tough motor and won't be bothered by something so minor. I was actually thinking about using it myself but I may just stick with dino in the Blazer. If you ask me people put way more thought into oil choice than is really needed. I use M1 0w20 in the wifes Honda mainly because I change it based on the oil life indicator so it usually ends up being 5-6k. Just use what you prefer as long as its nothing too crazy and keep it changed when needed.
 

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I use 5w30 which is what it calls for. Had truck new since 2003.
Used Valvoline Conventional for most of its life. Used some Mobil1 extended syn trying to see if it would really last looking good for 12k miles as they claim. I was only gonna do 6k mile test. But at 3500k miles it looked like any other oil so I changed it like normal. Got Valvoline high mileage (has 90k on truck now) in last change.
I always ran PF47 AC filter since new. Last time I went with the longer 4wd PF52 filter :)
 

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I use Mobil 5000 5w30 and sometimes the high mileage stuff but alway use a WIX filter.

Now in the TA I use 0w40 M1 but thats only because I rarely drive it and will change the oil yearly.
 

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Discussion Starter #16
I understand that those extended change intervals are only good on cars that are designed around that from the start and not just any car with a standard oil filter. I hear that often the oil is still good but the filter is used up long before the oil. Sure, you could put a new filter on and replace the lost oil but I am not going to go to all that trouble and mess without just changing all the oil at the same time.

I figured that the 0W40 probably wouldn't hurt a 4.3L. I understand the anti-wear and anti-sludge additives in this oil are far better than in the Mobil 1 0W30 and 5W30 oils. This, in addition to the fact that it is pretty common and relatively inexpensive for a high quality oil make it attractive.

I can attest to the fact that the 4.3L is one tough engine. I hydrolocked mine in a creek one time and pretty much assumed the engine was destroyed. I removed the spark plugs while standing in the cold water in my boxer shorts and blew the water out, only to have the truck fire right up and run fine. Of course I changed the oil ASAP when I got home.

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redneck extraordinaire
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I understand that those extended change intervals are only good on cars that are designed around that from the start and not just any car with a standard oil filter. I hear that often the oil is still good but the filter is used up long before the oil. Sure, you could put a new filter on and replace the lost oil but I am not going to go to all that trouble and mess without just changing all the oil at the same time.
That is generally the case. Standard oil filters are designed to filter for ~3000 miles. Obviously they don't plug up at 3001 miles but that's the interval they're designed for. Occasionally you might be able to run them longer depending on your driving conditions IF the manufacturer of the vehicle says so and you're using an OE oil filter.

I figured that the 0W40 probably wouldn't hurt a 4.3L. I understand the anti-wear and anti-sludge additives in this oil are far better than in the Mobil 1 0W30 and 5W30 oils. This, in addition to the fact that it is pretty common and relatively inexpensive for a high quality oil make it attractive.
Stick with the weight recommended by GM
 

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As bigghoss said 5w30 for stock motor. Conventional or synthetic your call. As far as brands im not real fussy, nothing recycled or no name. My 2 cents keep it changed every 5000 km.
 

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I use mobil 1 0-40 in all of my vehicles. I've had it tested and comes back with great results. Zinc lever is usually over 1000. Reg mobil 1 5-30 zinc is around 850 or so. Also the 0-40 mb 1 is one of the few oils that meets BMW's long life spec, which would lead me to believe it's a very good oil.
 

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redneck extraordinaire
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I've been told, back when I worked in a quick lube, that the major benefit to full synthetic is a noticeably increased lifespan in the engine if you keep up on the maintenance like you should. However this is if you run it for the entire life of the engine. Allow the engine to get about 30,000 miles to ensure a good break in (because supposedly it's too slick and the engine won't break in properly) and then switch over to full synthetic and stick with it. I'm lead to believe it also frees up some HP/mileage and can increase the intervals between oil changes but with the cost of the oil the economic benefits are a wash at best.

Anything beyond conventional or full synthetic (High mileage, synthetic blend, ect) is generally snake oil and a ripoff. At least that was the case back when I sold the stuff.

As for running 0w-30 or the like, that's the same as running 5w-30 in an engine that calls for 10w-30. Just run what GM calls for, MAYBE a viscosity higher in really hot weather and/or if the truck has a lot of miles. If your OP gauge reads a little low on a truck with a lot of miles than maybe try a thicker oil (but don't jump straight for the 15w-40 if it originally calls for 5w30).
 
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