I got my Blazer last September with about 64,000 miles on it and have changed the oil once so far, which was when I started using the Mobil 1 synthetic oil (unsure what was in it previously). I've always been a 3,000 mile on the dot kind of guy, but this is my first time using synthetic, and despite how strange it feels to me that I just hit 5,000 miles on this oil change, it actually does still look pretty clean to me, so I'm unsure if I should change it now or wait until 6/7,000 like I've heard is recommended for the Mobil 1 synthetic.

I want the best for the engine (I'm not trying to get the most out of my money), but I almost feel like it really would be fine to go a bit longer. What do you guys think? Hell, I'd use this oil and still keep to a 3,000 mile cycle if that would actually make a difference for the engine.

(This is the regular Mobil 1 synthetic oil, not the extended performance version which is apparently guaranteed to go a ridiculous 15,000 miles before changing.)

Edit: I just went out and changed it anyway. After seeing it in the pan, it definitely needed it. Since my goal is to maintain the truck as best as possible, I think I'm gonna stick to the good ol' 3,000 interval, even with the Mobil 1 synthetic and premium filter setup.

 

i use mobile 1 synth high milage and do it every 5k

 

+1, and I use wix filters

 

My .02 worth is the oil was nasty in the pan because of the previous owners (possible) neglect. Your 1st oil change looks like that from the old oil still sitting around in lines etc. Check it regularily (like I'm sure you will) & I bet it will go the 5000 miles at least before it gets nasty again.
If at some time you have the urge take the PS valve cover off & see if there are any deposits in the vallies etc. It's easy to do, no gaskets needed & only about 30 mins time. If there are deposits or other nastyness maybe try a Seafoam treatment in the engine just before the next oil change. Search in here for Seafoam & you'll get LOTS of ideas.

 

This was actually my second oil change, not the first one that had the previous owner's oil. The oil in it was my own Mobil 1 synthetic, that had 5,000 miles on it, and was pretty dirty in the pan. I think I'd be okay to go to 5,000 at the most, but I intend to just keep to 3,000 anyway. I appreciate your other advice - I will be doing that.

 

Hi everyone! New to the forum here...

I use Mobil 1 in all of my vehicles and change the oil and filter every 10,000 miles. I use 5-30 and Fram extended guard filters.

I pulled the engine out of my 2.8 liter supercharged S10 blazer at 140,000 miles to stuff in a 350. After pulling the 2.8 apart, all clearances were still within tolerance for a new engine. The cam was right at factory specs. ( I took the cam into a guy who grinds cams to have it checked out of curiosity...)

My '92 K Blazer (350) has 212,000 miles. It runs great. No smoke, no leaks, oil consumption is right at 1 quart for 10,000 miles. The engine might as well be new.

Numerous passenger cars have done perfectly with the same schedule, though I've sold them after they got over 125,000 miles...

So, yeah, I'm a firm believer in Mobil 1. I'm also convinced that 10,000 mile oil changes work fine with the stuff.

 

I use Mobile 1 Full Synyhetic in my 1989 Jimmy, My 2000 Jimmy and my 04 Volvo S60 R. I also used mobile 1 in my 1999 Subaru since the first Oil Change and I have given the car to my daughter and it has 205,000 miles and runs like new. The advantage of full synthetic is that there are no impurities so there is no build up of sludge and friction is reduced. I started with Mobile 1 but any full synthetic brand should be equal. Yes you can run longer intervals between Oil Changes. I switched to Mobile 1 when the Subaru was still under warrenty I contacted Subaru with regards to using full synthetic oil and their position was that as long as I kept to the service intervals listed in the owners manual the warranty would not be afffected. I have heard that using full synthetic can cause seals to leak. I have not had that experience in over 10 years of using synthetic oil,

 

^ switching from "regular" oil to synthetic can cause you to burn seals just becuse synthetic is so much finer and cleaner it can reach places regular oil cant....i have a 1980 Buick regal and i tryed synthetic in it once and it smoked the blues like ive never seen before ...but i run full synthetic in my blazer and its great but im old school still changing at 3000 no matter what lol

 

I use full synthetic in my 93 jimmy, I am not sure what the previous owner used before me, But since I had it, its been synthetic.
The valve seals have been leaking since I got it, little puff of smoke at startup, but it has not gotten worse, so I'm amusing the previous owner used synthetic.
Also, I change it ever 3k miles, synthetic or not.
I was thinking next time trying a synthetic blend and see what it does with the smoking at start up, but i heard going back to conventional oil after using synthetic is bad? is this true?

 

Sorry about the length of this post; I kept it as short as I could and still get out the needed information.

OK, several myths going around about synthetic oil. First off, let's understand what Synthetic oil is. Keeping it real basic so it's easy to explain and understand: Synthetic oil has had it's molecular structure modified so that the oil behaves like we want it to. What do we want it to do? We want it to flow and lubricate over a range of temperatures. We do not want sludge to form. There's a few other properties we need to get it to do those two things, but they all support those two requirements.

Synthetic oil is better than conventional oil because the basic structure of the oil is good at performing the above two objectives. Conventional oil requires additives to do the same thing. These additives burn off or evaporate over time, so the oil's lubricating properties diminish and it starts forming sludge. Synthetic oil will not deteriorate or form sludge until around the 25,000 mile mark. Conventional oil starts deteriorating the first time you warm up your engine. Conventional oil also is far more affected by temperature than synthetic.

OK, now to clear up some myths:

Why do we change oil? Three reasons. 1. It's lubricating ability deteriorates over time. 2. It forms sludge over time. 3. It gets dirty. So, with conventional oil it's imperative to change the oil every 3000 miles. Even if it is clean enough to remain in use, conventional oil deteriorates and forms sludge quickly. With synthetic oil we only care about the contamination in the oil. That will reach an unacceptable level before reasons 1 or 2 come in to play. When will that happen? Hard running and a dusty environment will accelerate the rate of contamination. Mild running, a clean environment and an oil based filter like a K&N will slow the process. (These filters trap fine dust better than paper elements.)

So how long is long enough? To know for sure, you'd have to do an oil analysis. Too much work, so we change Synthetic before it needs to be changed. Back a long time ago, I had access to oil analysis. I lived in Phoenix at the time, fairly dusty environment. I checked my oil at 10,000 miles once. This was on a supercharged 2.8 that had been run hard and wheeled a lot. The oil was fine. I live in Portland now. Very clean environment. Sometimes I get lazy and don't get around to changing the oil till 13,000 or 14,000 miles. No ill effects noted. As I noted above, my 5.7 might as well be new considering performance, smoke and leakage. It runs like new, it does not smoke, it does not drip. One quart oil use every 10,000 miles is good for a new engine, let alone one with 212,000 fairly hard miles on it.

As far as going back to conventional oil, sure it's bad. Conventional doesn't perform as well as synthetic. But it's no worse than running conventional oil in any engine. Nothing mythical happens when you run synthetic oil that makes switching to conventional oil any worse than starting out with it.

Changing to synthetic is always good, no matter how long conventional oil has been run. Sure, the engine might start to smoke a bit. Believe it or not, that's a good thing in this case. Why is the engine starting to smoke? It's not because the oil gets into places because it's finer. It get's into places because the synthetic oil is cleaning away sludge that has formed. That sludge has prevented the oil from getting where it needs to go. Now that the sludge is being washed away, oil is getting back to where it needs to go. Yes, the seals have deteriorated. That doesn't mean you should be without oil on those parts. Rather the opposite, you need lubrication more than ever so things don't start wearing at an ever increasing rate.

Is there a problem changing synthetic oil every 3,000 miles? Other than your time and money, of course not. I do think your time and money would be better spent elsewhere though. Certainly 5,000 to 6,000 mile changes should satisfy even the most demanding requirements.

Synthetic/conventional blends. Wow, what a total waste of money. The conventional portion will deteriorate and perform just like conventional oil, because that's what it is. The Synthetic portion just adds cost to the oil. The worst of both worlds. The weakest link determines the strength of a chain, and in this case the conventional oil determines the quality of the blend.

Switching from conventional to synthetic. Always a good thing. However, I'd go with a 2000 to 3000 mile change interval for two or three changes if the rig is high mileage. Why? Simple, the synthetic oil is going to be washing out the considerable dirt and sludge the conventional oil left behind. It's going to get contaminated a lot faster because of this. Your engine is also going to run a lot longer because of this.

If you know much about oil you'll notice that I really simplified the advantages and properties of synthetic oil. I just figured that this post would be more than long enough. Suffice it to say that synthetic is better in every way than conventional oil, except for cost per quart. However, if you change it one third as often, it actually becomes cheaper than conventional oil. (When you include filer cost and the cost of your time.) Conventional oil also deteriorates over time without ANY miles being run. A couple of months or so and you should change it regardless of mileage. Synthetic oil does not deteriorate over reasonable lengths of time. ( A year or two.)

It is ALWAYS better to run synthetic over conventional. Running synthetic oil with 10,000 mile change intervals is FAR superior to running conventional oil with 3000 mile change intervals. And cheaper.