Straight from the Mobil 1 website:
"The instructions are very easy to follow: Simply change the oil as you would normally. Any “confusion” is just myth. You can switch from conventional motor oil to Mobil 1 synthetic (and back again, if you want), without following any special procedures."

To achieve the best peace of mind related to engine protection, many vehicle owners change their engine oils every 3,000 miles. Is this practice rendered meaningless with Mobil Synthetic oils?
"Consumers should follow the maintenance practice meets their car manufacturers’ warranty. They can have peace of mind knowing the guaranteed performance and protection intervals of the Mobil line of oils is 7,500 for Mobil 1 and 15,000 miles for Mobil 1 Extended Performance -- guaranteed."


Would you like the link?
Maybe the engineer you talked to works for a different Mobil 1

Personally, if I had a mechanic try to sell me on paying him to change my full synthetic oil every 3000 miles, in a vehicle that wasn't beaten, day in and day out, I'd find a new mechanic rather than finance the guys next yacht purchase. But that's just me.

Now, I'm not saying to leave your oil in for 15,000 miles, but my point is still that oil & filter change frequency should vary by how you use your truck...

 

Penz Plat/mobil filter every 3500 for me..

As far as changing intervals, oil whether it's synthetic or dino will and does get dirty. Being synthetic doesn't change this fact and with synthetics "cleaning effect" it could actually get dirtier faster than dino. <--That's just a common sense guess so don't quote me on that.

Of course companies like mobil/amsoil/RP are going to suggest a longer change interval, they have to justify the extra cost to a "normal" person...a non gearhead person that needs some tangeable reason to justify the extra cost. They can't see the extra protection/cleaning effect synthetic offers and companies know this...but they can see the longer change intervals and that gives the consumer a warm and fuzzy. I personally think it's a bad idea..

 

Well put severedistortion, even though its synthetic its still oil, conventional and syn. Start life as the same base product, they add " synthetic additives" to make it more slippery and withstand temps a little better, but it still oil and it gets dirty, castrol says you can run 7500 miles with high mileage, and people believe it, people believe running platinum spark plugs for 100,000 miles is ok-no its not. Do you believe autozone's brake rotors and pads "last" because they say duralast? But like i said run your rig how ya like. As for the mobil 1 website, why not watch the t.v., its a sales gimmick to make you buy the product.

 

I guess if I "follow manufacture recommendations" that would be every 6000 miles per the manual in my '08. I think I'll be doing the first one at 3000 to switch to syn. and then over to the 6000mile mark

 

right, syn might actually get dirtier faster, but that's why i said before to CHANGE THE FILTER, its job is to take the larger dirt out of the oil. The smaller particles will still be there, but that isn't much of a problem.
Have you ever seen diesel oil? That **** is black, all the time. There is so much soot in diesel it turns black a couple weeks after it's been changed, but it doesn't need to be changed because the oil keeps the soot from doing damage to internal parts. in gas motors synthetics are better at that than dino oils are, so they can take a lot more dirt in them before it is time to change.

Oil needs to be changed when it starts breaking down, when it is running out of additives, or when it ends up with too many small particles in it. Synthetic is much better at holding itself together, and is packed with much much more additives than dino oil. If you're not driving down a sandy dirt road every day, the small particles won't be an issue.

Bout 4 years ago I was of the same thought as police and severe, my dad wanted to switch to mobil 1 and leave it in for 10k, i was strongly against it. then i started working at places that deal directly with this and do these tests, and I saw actual results and what actually happens. I didn't talk to an engineer that talked to a marketing rep. I am an engineer, and I saw it myself. After seeing all the results, I finally did my first synthetic change a month ago, and plan on leaving it in for quite a bit longer than 3k.

 

I didnt talk to an engineer that in turn talked to a rep., i talked to one of the guys that makes the stuff( an engineer) not the rep. I have also torn down engines, both with syn. And conventional oil, and still i wouldnt leave any oil in for more than 3,000miles, in its base form oil is oil, and with high temps and friction it might last a little longer than 3,000 miles, but not 6-7,000 miles hell no. Lol-does anyone around here believe the government when they tell us there is an oil shortage? Haha, we have enough oil for the next 50-75 years, but they dont tell us that-you think mobil or castrol is going to tell you syn. Lasts for only 3,000 miles-no, because then you wouldnt buy it because of cost. It all about the almighty dollar

 

no, i don't believe them. i also feel i have more of a contribution to preventing the next ice age than causing global warming. But changing from oil to some other energy isn't going to happen overnight, it's a good time to get started on converting.

no i don't expect them to tell me that. but i expect test results to tell me, but they don't either, they tell me the opposite, that synthetics DO LAST LONGER.

That is all. I will now remove myself from this beaten to death topic.

If you can bear to continue Hammer, I wish you good luck.

 

Since this topic has been beaten to death....what about extended intervals on MDS rams?

I mean, DCX and most people on here are adamant about using 20w over 30w for MDS hemi's...if that small of a difference could effect MDS don't ya think extra dirt could? Everyone knows the hemi uses the pushrods for lubication (which could also be a trouble spot)...i'm wondering what the effect would be on the MDS solenoids and extra oil passages.

 

Since I don't have an MDS Hemi, I can't look it up, but what does the book say?


And Feejay, easy there hoss. Some people are set in their ways, everybody is going to have a different opinion. If the guy is taking care of his customers and they are happy paying him for oil changes with a full synthetic every 3k, that's fine. Hell, being over-cautious and changing every 3k certainly isn't going to damage an engine. I personally don't agree, even though for the most part I've always changed my oil at 3k in my trucks, but that's because I work & play harder than most. My ex's GC's got changed every 6k because they were commuter vehicles. I especially don't agree with the man's filter choice, you go around most southern garages and mention his filter choice and you'll get nasty looks. They do have a reputation of not filtering well. But if he's man enough to stand behind his work, fine. There is no reason for you to get bent out of shape over it. Life's too damn short...

 

In its base form, synthetic does not contain the contaminants that cause sludge and other harmful deposits. The additives will eventually wear out, but as long as the oil is not exposed to excessive heat, the actual base oil will not wear out.

And as modern engines, with their close tolerences, do not permit the blow-by of engines in years past, the oil does not get contaminated with combustion by-products like they used to.