# Switching To Synthetic Oil



## Morrowmd (Feb 22, 2005)

Next oil change I am going to switch the engine oil on the Tahoe to synthetic and I've got questions:

*Mobil 1 or another brand, which is best?
*Do I need a special filter?
*Are there any special steps I need to take to insure all the old oil is drained?
*I assume I will be able to go longer intervals between changes- how long?
*Anything else I need to know?

I plan on doing oil changes myself to offset the price of synthetic. I will also in the future be going to synthetic transmission fluid but I'll let my mechanic handle that one.

Any advice is appreciated!









-Matt


----------



## PDX_Doug (Nov 16, 2004)

Matt,

I like Mobil-1 myself, but am sure the synthetics from any of the major brands will do equally well (Valv-o-line, Quaker State, etc.). The important thing is that the grade matches or exceeds the manufacturers specs for your rig.

When changing, I think it is a good idea (but probably not necessary) to flush the system as much as possible. That may be tough if you are doing it at home.

Mileage wise, you should get at least twice the distance between changes (say 6,000 miles), which is good, because the oil is going to cost you at least twice as much!









All in all, a good 'mod' to be making to your rig. From a towing perspective, the tranny and differential(s) will benefit even more than the engine.

Happy Trails,
Doug


----------



## NJMikeC (Mar 29, 2006)

Mobil 1 or Castrol Syntech.

Mobil1 is put in all Mercedes Benz and BMW uses Castrol. That should be proof enough. BMW actually has a 15,000 mile oil change interval although I do mine at 7500.

For my TV I use Mobil 1 and I change mine at 6,000 miles. If I do a lot of towing throughout the summer then I change closer to 4,000 miles just because I'm a worry wart and that my truck calls for 5W-30.


----------



## NJMikeC (Mar 29, 2006)

ANOTHER VERY IMPORTANT THING IF YOU ARE NOT USED TO DOING YOUR OLD OIL CHANGES.

MAKE SURE THAT THE GASKET FROM THE OLD FILTER IS OFF THE ENGINE. I ENSURE THAT BY LUBING THE NEW FILTERS GASKET BY RUBBING IT ON THE OLD FILTERS GASKET.

IF YOU LEAVE THAT GASKET ON THEN YOU WILL LIKELY BLOW UP YOUR MOTOR.

I have seen that done on cars, trucks, snowmobiles, motorcycles. It is sickening quite frankly how often it happens as I have seen several garages do it.


----------



## GlenninTexas (Aug 11, 2004)

Back when I was driving a lot I used Amsoil and an Amsoil filter. The filter was much finer 3 microns I think. I changed oil every 18,000 miles. The engine was a 2.8l v6 in a Chevy Blazer. It had over 160,000 miles on the engine when I sold it and was still running strong.

I intend to switch to Amsoil in my diesel and use their filters. In addition, I'm thinking seriously of putting on one of the Amsoil bypass filters.

Regards, Glenn


----------



## OutbackPM (Sep 14, 2005)

GlenninTexas said:


> I intend to switch to Amsoil in my diesel and use their filters. In addition, I'm thinking seriously of putting on one of the Amsoil bypass filters.
> 
> Regards, Glenn
> [snapback]118378[/snapback]​


 Using the AMSoil and filter is a popular choice. If you do a search on amsoil you can find many leads. The other popular choice is mobil-1. From what I have read these guys do thier own work so are up on the technology. A test I saw somewhere put the two equal on many paramaetrs. Either will work its what you can best obtain.
On my diesel I plan to use amsoil with thier filter and (for the diesel with an EGR valve with alot of soot build up in the sump) I am considering an FS2500 by pass filter as well. I have not seen good reviews of the ams bypass filter for the D/max application but that is lack of first hand experience on the reviewers part so if it is in line with the rest of thier oil products it should be good.


----------



## OVTT (Mar 31, 2006)

Mobil 1 is great for a product you can purchase anywere. If you can find Amsoil it will be the superior product and your engine will thank you for it. Also check with your dealer but I am told that the tranny already runs synthetic.


----------



## tdvffjohn (Mar 10, 2005)

I have not done the Duramax yet, but for all of my gas engines I have used Mobil 1. I change every 5000 miles because I do not have to write it down, 20,000, 25,000, 30,000 etc. Simple, easy to know when its due.

We opened one engine( that I installed new) when it had 110,000 miles on it to check the timing chain (the engine was out for a restoration, street rod project) and it was spotless and had never used any oil.


----------



## biga (Apr 17, 2006)

My dad has been a mechanic all of his life. Master mechanic, has worked for mostly Nissan and Toyota dealerships. He has always said that regular oil changes are much more important than what oil it put in the pan. If the factory filter for you engine has an anti drainback valve, your replacement should have one also. It is there for a reason. Check your oil often, especially in extreme use (such as towing a trailer).

From my own experience, I don't use synthetics any more because both vehicles I tried it in developed oil leaks within the first oil change. Both of them were near 100,000 miles. On the second oil change they got worse. The third change got good old dino oil. After a couple years and 40,000, one of the vehicles has basically stopped leaking. The other still leaks after 60,000 miles.

Those are my thoughts. Take them for what they are worth.









Now, if I only followed my own advice.


----------



## gregjoyal (Jan 25, 2005)

OVTT said:


> Mobil 1 is great for a product you can purchase anywere. If you can find Amsoil it will be the superior product and your engine will thank you for it. Also check with your dealer but I am told that the tranny already runs synthetic.
> [snapback]118396[/snapback]​


My Chevy has Dexron III in it... I'm pretty sure it's not synthetic. From what I've read, it is regarded as a pretty high quality fluid.

Your dealer may be guilty of the all-too-common 'telling you what you want to hear' syndrome that dealers of any kind tend to suffer from.

Dexron III


----------



## madmaccm (Oct 7, 2005)

Hi Matt,

I have been using Mobil-1 with my Titan and been changing it every 6K.

Works for me.

C-Mac


----------



## Lmbevard (Mar 18, 2006)

I have used Mobile One in my '98 GMC Safari for a couple of years. I use to tow my popup with this van. I had read in another forum of a guy pulling a popup up the mountains in CO. and having most of the oil boil off by the time he got to the top. He switched to Sythetic and made the same trip with no problems at all. Some people have had problems with leaks after switching so if the TV has higher mileage you might have problems. I had 50,000 mile on the van before switching and didn't have any problems. Mobile claims 10-15,000 between oil changes, but with towing, probley better to be conservitive. I usually have it changed at Wal-mart, it was cheaper than buy the oil and changing myself. Did nothing special when I switched, just changed it.


----------



## Oregon_Camper (Sep 13, 2004)

Ok, I'll ask.

Are they really that much better? Seems like a high cost...and I'm not sure where the ROI is?


----------



## Morrowmd (Feb 22, 2005)

Oregon_Camper said:


> Ok, I'll ask.
> 
> Are they really that much better? Seems like a high cost...and I'm not sure where the ROI is?
> 
> ...


Lately it seems every person I have talked to that tows a camper or boat swears by synthetic fluids- engine oil, tranny fluid, gear oil, (any others?).

I have in the past been a staunch believer of just changing my oil on schedule using a good brand name. I'm starting to believe that there must be something to this synthetic stuff.

I did not know about the problem with leaks, though.


----------



## BoaterDan (Jul 1, 2005)

Morrowmd said:


> I have in the past been a staunch believer of just changing my oil on schedule using a good brand name. I'm starting to believe that there must be something to this synthetic stuff.


Back when synthetic oil started getting popular (maybe 15 years ago??) there was lots of magazines etc. testing the claims. The biggest issue is that it is a gazillion times better at handling very high heats. At temperatures that had essentially turned traditional oil into pudding the synthetic was still humming along not missing a beat.

I just replaced my rear end gear oil with synthetic. On return from the last trip I noticed oil spattered all over the front of the TT. Inspection showed it had blown out the vent hole of the rear end. I don't even want to describe what came out when I drained it. Bottom line is that factory crap had just pretty much completely broken down and turned to a nice meringue!

Over the next year or so I'm going to change every fluid I can to synthetic.


----------



## LateralG (Feb 11, 2006)

Morrowmd said:


> Lately it seems every person I have talked to that tows a camper or boat swears by synthetic fluids- engine oil, tranny fluid, gear oil, (any others?).


Air is a fluid.


----------



## tdvffjohn (Mar 10, 2005)

I thought is was a gas


----------



## cookie9933 (Feb 26, 2005)

tdvffjohn said:


> I thought is was a gas
> [snapback]119097[/snapback]​


It is. But the retired engineer was giving you the textbook definition of a fluid, which can be either gas or liquid. Basically if something conforms to the shape of the vessel holding it, it's a fluid. This is because the molecules are free to move.

Bill


----------



## NDJollyMon (Aug 22, 2003)

BoaterDan said:


> Morrowmd said:
> 
> 
> > I have in the past been a staunch believer of just changing my oil on schedule using a good brand name. I'm starting to believe that there must be something to this synthetic stuff.
> ...


My TITAN factory differential oil looked like black paint, and smelled BURNT after 5,000 miles! I changed it to synthetic right away. No probs since. Newer TITAN's come with syn oil in the diff now.

Changed the engine over to Mobil 1 after 10,000 miles on dino oil.

I took it in for an oil change, and they put regular dino oil back in it. I forgot to remind them when I arrived at my appointment. I'm switching it back in a few more miles.


----------



## outbackgeorgia (Jan 28, 2004)

DC recommends synthetic in front and rear diffs in my Durango for towing (which I use), but NOT in the transmission, even towing? They have their own trans fluid specs.

Outbackgeorgia


----------



## aantolik (Apr 8, 2005)

biga said:


> My dad has been a mechanic all of his life. Master mechanic, has worked for mostly Nissan and Toyota dealerships. He has always said that regular oil changes are much more important than what oil it put in the pan. If the factory filter for you engine has an anti drainback valve, your replacement should have one also. It is there for a reason. Check your oil often, especially in extreme use (such as towing a trailer).
> 
> From my own experience, I don't use synthetics any more because both vehicles I tried it in developed oil leaks within the first oil change. Both of them were near 100,000 miles. On the second oil change they got worse. The third change got good old dino oil. After a couple years and 40,000, one of the vehicles has basically stopped leaking. The other still leaks after 60,000 miles.
> [snapback]118439[/snapback]​


My brother has an vehicle repair garage & he agrees that the frequency of oil & filter changes are the most important aspect as long as you use a quality motor oil. As far as synthetic goes ( I run Mobil 1 & have used Castrol in the past) the only time he has seen problems has been with vehicles with higher mileage on them before they were switched to synthetic.


----------



## GeoWalls (Jun 3, 2006)

About a year and half ago I switched to Amsoil and their filter. Their oil and filters are rated to last a year. It would be up to you if you let it go that long. But I think it works great. After switching my gas mileage when up a bit so I'm happy. Its alittle more expensive, but I think worth it. Also I work with a dealer and he had his oil tested after a year in his vehicle and there were no problems with it. I plan putting amsoil in my differentials also.


----------



## DANJOGAVINMO (Apr 17, 2004)

I've been using synthetic blend Shell oil in my rigs for 2yrs or so now. I change every 7500 in the Honda (wifes car) and still at 3000 miles in the truck even though I may not have to. Cost isn't an issue for me, my father works for a shell oil distributor









Have not had any issues (leaks, etc).

Danny


----------



## BoaterDan (Jul 1, 2005)

outbackgeorgia said:


> DC recommends synthetic in front and rear diffs in my Durango for towing (which I use), but NOT in the transmission, even towing? They have their own trans fluid specs.
> 
> Outbackgeorgia
> [snapback]119177[/snapback]​


I believe GM is the same. I'm going to check with a local highly trusted tranny shop and see what they say when I get around to that paticular fluid.


----------



## bill_pfaff (Mar 11, 2005)

BoaterDan said:


> outbackgeorgia said:
> 
> 
> > DC recommends synthetic in front and rear diffs in my Durango for towing (which I use), but NOT in the transmission, even towing?Â They have their own trans fluid specs.
> ...


Let us know please Dan as I'm looking at the same scenario


----------



## OutbackPM (Sep 14, 2005)

BoaterDan said:


> outbackgeorgia said:
> 
> 
> > DC recommends synthetic in front and rear diffs in my Durango for towing (which I use), but NOT in the transmission, even towing?Â They have their own trans fluid specs.
> ...


In the 2500 GM put synthetic in the rear diff. but not in the front on the 4x4. This months 4Wheeler has a good write up on diff oil and towing. Temperatures can get very high without really trying to. When towing it looks like the best thing for the diff is to use synthetic.


----------



## PDX_Doug (Nov 16, 2004)

DANJOGAVINMO said:


> Cost isn't an issue for me, my father works for a shell oil distributor


So... Danny! Buddy!









Happy Trails,
Doug


----------

