2005 Tahoe Gas Mileage Got Bad

[Bald Jerry]

I have a 2005 Tahoe and use Lucas Full Synthetic Oil with their Synthetic Stabilizer and have been using it pretty much since I got it... Actually started out with Mobil One Full Synthetic... I run the Lucas Deep Fuel Treatments through it every oil change, K&N Air Filter had for years gets cleaned every oil change as well... Use quality fuel which is Shell for many years....

I was getting a combined I would say around 15MPG and on trips would break just over 20MPG no problem... Now, 12.5 combined and lucky to get 16MPG Highway... I have about 65,000 on it and it runs great... No error codes show up on the computer....

I was reading some article on cleaning O2 sensors... Anyone think that makes sense??? Or any other suggestions????

 

[clkelley]

My personal opinion is that if you should not have to use oil stabilizers if the oil itself is doing what it is suppose to do. Running stabilizers all the time thickens the oil viscosity and over time can cause more harm than good. You should have stuck with Mobile or if you weren't happy with it, then changed to something that was actually better, Lucas is not the best choice out there.

I personally have run Amsoil in everything I own for the past nine years or so and have been a dealer for them since 2007. On the wife's 04 Denali that we got bought last year with 80K on it, I immediately changed ALL the fluids over to Amsoil and on the highway we regularly average between 18-19.5 depending on my right foot and our overall average is 16 right now.

That being said, I have also gone through and replaced the air filter, cleaned the MAF sensor and throttle body, replaced the plugs and o2 sensors. Doing all the required maintenance would definitely help.

 

[Bald Jerry]

Thanks.... I will give it a shot and switch over... Mobil Synthetic was good, but I should should have put this in once I switched over to Lucas with the stabilizer my mileage got even better....

I am going to give Amsoil a try on the next oil change, stop using the stabilizer, and do the things you suggested and see what happens. One other thing I heard that their is a summer fuel and a winter fuel (I am in Chicago). In winter my mileage is even worse and I am not comparing that to warming the Tahoe up. I am comparing it to when I go up to my place in Wisconsin with a warm engine, just stopped for fuel, and when I get up their the mileage is way down.

Now since we are finally getting warmer here (strange winter and spring here temperature wise) mileage got a little bit better... Just curious if that is true about a summer and a winter fuel...

 

[Bald Jerry]

I was looking up Amsoil Synthetic and they have a couple different oil change intervals and here is the one that will apply to me...

For me using the Tahoe the way I do it says change it every 25,000 miles or once a year????? I am sure oils have gotten a lot better over the years and I know synthetic is much, much better than conventional oil hands down. From what I also was told by a Dealership that synthetics do not breakdown like conventional, and you are pretty much just changing it because it is dirty...

I am no mechanic, chemist, etc, but to me Amsoil saying change it every 25,000 miles or once a year seems to be stretching it pretty far. I know they use to say every 3,000 or 3 months on conventional oils, but like I said above I know oils have improved since then quite a bit I am sure.... I am sure it is great on your wallet changing oil the way Amsoil is saying every 25,000 or once a year, but do they have any testing that backs that up? I am not sure how long Amsoil has been around, but did they take a vehicle and actually do this or take a motor and simulate this?

To me it sounds crazy with the prices of vehicles now a days to trust that. I would love to see some testing they have done to prove that it only needs to be changed every 25,000 miles or once a year.

I know you said you are an Amsoil Distributor and I would guess you would have access to getting that to see if they ever did any test with their oil change interval schedule.

Do they have any tests or proof on that??? How often do you change your oil at? Do you go by what they are saying the 25,000 or every year? Whats your recommendations on oil change intervals? Do you agree with Amsoil???

 

[clkelley]

AMSOIL Synthetic Lubricants Incorporated & Their Claims...

I am actually glad you asked all those questions. First let me start by saying that as I provide these answers I am going to be providing links to just a few of the Amsoil testing informational PDF's provided by Amsoil, while other links will be to oil analysis testing results performed by other customers and dealers in my personal account group. I will provide both so that you can see not only labs testing results, but also real world results to back up the claims made by Amsoil Inc.

First, let me start by saying that AMSOIL Inc was founded in 1972 by AL Amatuzio after seeing the benefits provided by synthetic lubrication for jet fighter engines under MUCH more stressful conditions than seen in the automotive industry. CLICK Here to watch a video presentation to learn more about that.

Amsoil was the very first company to offer full synthetic lubricants to the automotive industry and was offering GUARANTEED 25K mile oil change intervals even then. Although other companies like Mobile attempted to do the same, they had to stop because their lubricants just didn't hold up.

Amsoil has remained the leader in the synthetic lubrication industry ever since. They actually do more real world as well as lab testing on their products than most other synthetic lubricant manufacturers for one simple reason, as vehicle manufacturing and engine development changes and becomes more sophisticated, so should the oils designed to protect them.

Here are a couple of helpful links to some of the testing that Amsoil has done in the past to help provide consumers with verifiable information to ease their minds about the viability of their claimed service intervals.

AMSOIL Comparative Motor Oil Testing

409K Mile Oil change Interval Road Tractor Engine Tear Down Information

930K mile engine information

Understanding Engine Oil PDF

Why Using "Oil Additives" can be harmful



That being said, my personal experience with Amsoil began about 8 years ago when a friend of mine who owns the local Carquest began to recommend Amsoil to me and was claiming 12,500K mile intervals for my diesel. Well, like you I just didn't believe it, I was at the time running Mobile 1 and changing every 3K in everything I owned. But, over time he kept at it and finally I tried it. The things I noticed right off the bat were a quieter running engine in my diesel, and my gas engines, less lifter knocking at start up, etc. But I still didn't feel comfortable extending intervals just on the word of the company that sold the lubricants whether they were synthetic or not.

So, after awhile I decided for several reasons that I wanted to begin a business online and as a part of that I decided to do some more checking into Amsoil and their extended service interval claims. I found a LOT of information online and the one thing I found interesting was that the ONLY complaints I ever saw had more to do with the way Amsoil advertises than the quality of the lubricants. I have NEVER actually seen ANYONE have a verifiable complaint about the Amsoil synthetic lubricants not holding up to their claimed service intervals. EVER. So, I found out how to become a dealer for their products and along the way I began to perform oil analysis to back up my extending my own intervals. Now, my analysis results were in my diesel Duramax using their Diesel & Marine 15W-40 full synthetic diesel oil and their newer CJ-4 5w-40 full synthetic diesel oils, and I found that with the diesel & marine 15w-40 I could go at least 23K miles, (when I changed to test the 5w-40 in my LB7 Duramax). I personally didn't like the CJ-4 rated diesel oil results in my LB7 so I switched back to the 15w-40 D&M and basically began to change it once per year after that because the oil had more than proven itself to me personally, especially considering how hard I am om my Duramax.

That being said, most of the dealers and customers in our group, while they also run Amsoil in their gas engines, most of them are into diesel trucks and have done their testing on those vehicles. That being said, I am going to link you to a couple of the testing results just to give you an idea of the results others are seeing using used oil analysis to verify and back up the claims by Amsoil, so that they are not just extending their own service intervals by blind faith in the claims made by Amsoil synthetic lubricants incorporated.

Please note that there are several factors that lead to different results, and if you want to know more about used oil analysis testing, trending, when to test, how to test, or whatever the case may be feel free to ask as I have provided much of that information on our site as well.

AMSOIL Dealer Travis Reinke's 2008 Duramax Oil analysis testing results thread.

AMSOIL Dealer Trevor Greene's Oil analysis testing results

AMSOIL Dealer Willie Parsons Oil analysis trending thread.

In closing, Amsoil synthetic lubricants incorporated is NOT a fly by night, new company making outrageous claims that cannot be backed up. I have tested myself to ensure this as have many many people over the last 40 years. The biggest difference between Amsoil inc and other lubrication companies is that they do not use the more common forms of advertising like tv and radio commercials to advertise like the other lubrication companies out there. ALL advertising you may see for Amsoil products is provided by independent Amsoil Dealers like myself so that we have the opportunity to not just work FOR Amsoil and make a salary, but to actually use Amsoil and their products to help build our own businesses for greater future success, growth and security than a simple job can provide.

Again, I thank you for looking into Amsoil products and hope that you will look further into the information I have provided and get back to me with any and all questions that I am willing to bet you will have later.