Perhaps I did not search correctly but I did not see a thread here about people using synthetic oil and their experiences.TALKING GASOLINE TRUCKS USED TO TOW HERE: For example, if you ARE using synthetic oil, does it help truely with your mpg? Does engine perform better when towing or run cooler etc.?Also are you using any other type of oil aditive that has HONESTLY helped with mpg.? Example "SLICK 50" etc. Good results as well as horrow stories welcome.Thanks,Andy

I tried it in both diesels I've owned.No difference what so ever.

4 miles per hour difference for me

Synthetics along with any other "additives" are nothing more than snake oil as far as MPG goes.What many vehicle manufacturers have been doing to "help" the mileage is to spec oils which are much wider in cold to heat range. In other words now days 5W-30 or 5W-40 is the "recommended" oil specs. Older vehicles the specs were 10W-30 or 10W-40 or 15W-30, 15W-40.The idea is the lower the oil spec the thinner the oil is when cold and this "helps" reduce the friction of the cold oil.Where synthetics "shine" is in longevity, often can go a few miles longer on the oil changes. However the extra premium price of Synthetics sort of takes away this advantage in cost per quart..If you are looking to "gain" mileage you have several choices... Lighten up on the go pedal OR trade your vehicle in for a "smart car".. But really there is NOTHING you can dump in your oil or gas which will increase mileage inspite of folks who make "claims" that it helps them. SAVE YOUR MONEY and don't bother with marketing gimmicks.

I just traded in my 2004 Silverado with a 6.0L engine and 140,000 miles. I used it to tow a 10,000# FW in the mountains of Arizona to Montana. I replaced the factory oil with Mobile 1 full synthetic at 200 miles, then used synthetic for every oil change since then. I changed the oil based upon the Oil Sensor system. When the light came on, I changed the oil. At 125,000, I developed a small leak over one of the rocker arm covers. I removed the cover and replaced the gasket. What was amazing was that the rocker arms and top of the cylinder head look brand new! There was no sludge what-so-ever. I would not say I got any better gas mileage than anyone else, but I felt much more confident in the longevity of my engine when using synthetic. I also had a 1989 Mistubishi Montero that I'd purchased new. My wife and I commuted in it over 100 miles per day. When I traded it in several years later, I had 245,000 miles on the engine and had zero work done to it other than routine timing belts per the owners manual.I know this is anecdotal evidence, and others probably have similar results with petroleum based oils, but there was no sense in me changing from what worked.

Anybody using synthetic oil? Help with MPG? etc.

25 Replies

BeerCan
Explorer
Aug 15, 2013
Synthetic does not have the meaning it used to. Used to be a synthetic oil was either group V esters or group IV PAO. In the late 90's Castrol changed its formula from PAO to hydro-cracked group III oil which is mineral based. It lead to and industry fight mostly between Mobil and Castrol over the definition of synthetic. Mobil objected to classifying group III as synthetic, but eventually lost out. Just FYI it was not a lawsuit that occurred but a complaint filed with the National Advertising Division of the Better Business Bureau. They ruled that Castrol was not falsely advertising as Mobil had asserted.

Fast forward to today and most "synthetic" oils on the shelf are actually mineral oil based. A few of the boutique oils are true synthetic as are some of the European oils. AFAIK Germany and a few other companies only allow the word synthetic on "true" synthetics.

No need to worry though, the oil that is on the shelf today is great stuff. The refiners have progressed their science so far that even mineral based oils are lasting 15k or more. So as said earlier synthetics are about marketing and not performance.

I hope I got the details right LOL
Gdetrailer
Explorer III
Aug 14, 2013
gmw photos wrote:
Some current cars come with synthetic as factory fill, and the manufacturer of course recco's using synthetic when it is time to change it.
For Mobil 1 much of and sometimes all of the cost difference between it and conventional oil can be mitagated by watching for it to go on sale at walmart.

Some engine designs benefit, in fact may "need" a very thin oil for small oil passages in the engine. Synthetic can be an advantage on cold startup, in cold weather for an engine like that.

If you really want to know how you oil is doing, take a sample and send it to a lab for testing. I use blackstone lab, but there are others. Blackstone charges $25 for an analysis.

:R

B.S. Light just went on.

BOTH "DINO" and SYNTHETIC oils use the EXACT SAME oil weight RATINGS.

In other words Synthetic oil rated 5W-30 WILL ACT THE SAME as 5W-30 DINO oil.

There is no "magic" in Synthetic oil that will allow it to pass through "smaller" oil passages. If you believe otherwise I can make you a great deal on some Ocean front property in Arizona..

Basically Synthetic oils allow for a bit longer interval between oil changes, costs more too boot. So in the end you STILL pay more for it and change the oil one or two times less during the vehicles life gaining no extra mileage or LIFE of the vehicle.

Synthetics are all about great marketing, appeals to folks who really HOPE to squeeze better mileage out of the vehicle which is what the marketing groups appeal to.

I have one vehicle currently with 200,000 miles on the clock, run it solely on DINO oil and doesn't make any odd noises, doesn't burn oil between changes, in fact gets oil changes at 7,000-8,000 miles.

I am not buying it that Synthetics are that much better.
gmw_photos
Explorer
Aug 14, 2013
Some current cars come with synthetic as factory fill, and the manufacturer of course recco's using synthetic when it is time to change it.
For Mobil 1 much of and sometimes all of the cost difference between it and conventional oil can be mitagated by watching for it to go on sale at walmart.

Some engine designs benefit, in fact may "need" a very thin oil for small oil passages in the engine. Synthetic can be an advantage on cold startup, in cold weather for an engine like that.

If you really want to know how you oil is doing, take a sample and send it to a lab for testing. I use blackstone lab, but there are others. Blackstone charges $25 for an analysis.
BenK
Explorer
Aug 14, 2013
5W-30 to 5W-50 all have the SAME viscosity at room temp...5W

It is how the viscosity changes as the oil temp increases...they all
thin out (lowers viscosity) as their temp raises

The difference is how that curve looks over its temp range

At a top temp. A 5W-30 will have the viscosity of a single
30W oil. At that same temp, the 5W-50 will have the viscosity of a 50W oil

Again, both examples at room temp will have a viscosity of 5W.
beemerphile1
Explorer
Aug 13, 2013
Use what the manual calls for. Many modern vehicles do not use 40w oil.
RVer_Andy
Explorer
Aug 13, 2013
beemerphile1 wrote:
RVer Andy wrote:
...looks like the high quality 5W 50 oil is about the best one can do....

What gas engine manufacturer recommends 5w 50? That is some heavy viscosity oil. Nothing I own will be using it. I know some guys use 50wt oil in air cooled engines like a Harley. Even then I doubt the manufacturer recommends it.

My mistake, I meant 5W-40 someone above said that weight was OK to use. I plead ignorant about oil weight specs and always have been. Somehow the meaning of the numbers just doesn't stick with my 64 year old brain any more :?
RVer_Andy
Explorer
Aug 13, 2013
BenK wrote:
As with anything...all things...it is a system and to only look at one
aspect is to potentially take it out of context

Marketing folks do that all the time...take something or one component
of the whole out of context.

Yes, synthetic 'can' produce or allow higher MPG, but depends

Depends on stuff like what type of ICE, size of that ICE, architecture
of that ICE, the load (empty, small 'car' or towing several tons, etc),
terrain, ambient, and the two biggies: #1 how you drive and #2 your
maintenance schedule

I didn't know that there was different weights of ice. Is water lighter in some areas? What about dry ice? I guess lite beer would save help with the mpg also.
Take my 'ex' and her driving style, terrain, ambient etc...

Mud hen recycled jug oil would be just fine, but she doesn't maintain
it well. So one of my 'ex' sedans now smokes a bit (her new BF's driving
style doesn't help). Know this because she still uses the my mechanic

I used to fill with Mobil 1 synthetic and PureOne filters. Tried leaving
it in there over one year...but just could not stand it. So changed
it...old oil came out just as clear as the new charge going in

My Sub had a fresh charge of Mobil 1 synthetic and new filter installed
for a trip towing my old +8.5K lb boat up to Lake Tahoe a few years
ago. Noticed the gang was running much harder and figured showing that
one loud mouth who constantly bragged that his half ton Toyota could
out tow 250's, 2500's, etc

Okay, I'll join and nailed the throttle most of the way. That loud
mouth had to take in his Toyota and the kid next door to me worked
at the local dealer. Told me a new automatic and diff were installed

At just over 500 miles on that charge, noticed my big block consume
about 1 quart, dash oil PSI gauge fluctuated and lower PSI...changed
the engine oil and all went back to normal...must have worn out the
additive package and film/shear/etc strength of the engine oil reduced
Ditto flushed the 4L80 and diff fluid with sythentics

Film strength, temp range (high end is the main criteria) and the
additive package are the key differences between 'regular' oil and
synthetics. Then the different oil OEMs and how they refine the stuff

My big block ICE won't notice dino vs synthetic, as the pumping losses
of a big block has the differences in the two types of oil lost in that

Now my 2 seater and the old 2.4L in-line six does show the difference
as the pumping losses are no where near what my Sub's big block are

There are too many attributes, studies, etc, etc, etc to discuss on
this thread. I've been studying automotive via boy racer passion since my teens

My first charge of synthetic had one quart cost as much as my hourly
wage. Where the whole 'it is good for 20,000 miles' comes from, IMHO

Today's dino is most likely better than the synthetic's back then
wildwest450
Explorer
Aug 13, 2013
beemerphile1 wrote:
What gas engine manufacturer recommends 5w 50?

Maybe he meant 5w30? My truck has 398,000 miles on it and i've always used Mobil 1 full synthetic, changed every 8,000 miles, it still doesn't burn a single drop between changes. I don't care about mpg, not when I haven't made truck payment in 4 years.

I would never use anything different.
beemerphile1
Explorer
Aug 13, 2013
RVer Andy wrote:
...looks like the high quality 5W 50 oil is about the best one can do....

What gas engine manufacturer recommends 5w 50? That is some heavy viscosity oil. Nothing I own will be using it. I know some guys use 50wt oil in air cooled engines like a Harley. Even then I doubt the manufacturer recommends it.
BenK
Explorer
Aug 13, 2013
As with anything...all things...it is a system and to only look at one
aspect is to potentially take it out of context

Marketing folks do that all the time...take something or one component
of the whole out of context.

Yes, synthetic 'can' produce or allow higher MPG, but depends

Depends on stuff like what type of ICE, size of that ICE, architecture
of that ICE, the load (empty, small 'car' or towing several tons, etc),
terrain, ambient, and the two biggies: #1 how you drive and #2 your
maintenance schedule

Take my 'ex' and her driving style, terrain, ambient etc...

Mud hen recycled jug oil would be just fine, but she doesn't maintain
it well. So one of my 'ex' sedans now smokes a bit (her new BF's driving
style doesn't help). Know this because she still uses the my mechanic

I used to fill with Mobil 1 synthetic and PureOne filters. Tried leaving
it in there over one year...but just could not stand it. So changed
it...old oil came out just as clear as the new charge going in

My Sub had a fresh charge of Mobil 1 synthetic and new filter installed
for a trip towing my old +8.5K lb boat up to Lake Tahoe a few years
ago. Noticed the gang was running much harder and figured showing that
one loud mouth who constantly bragged that his half ton Toyota could
out tow 250's, 2500's, etc

Okay, I'll join and nailed the throttle most of the way. That loud
mouth had to take in his Toyota and the kid next door to me worked
at the local dealer. Told me a new automatic and diff were installed

At just over 500 miles on that charge, noticed my big block consume
about 1 quart, dash oil PSI gauge fluctuated and lower PSI...changed
the engine oil and all went back to normal...must have worn out the
additive package and film/shear/etc strength of the engine oil reduced
Ditto flushed the 4L80 and diff fluid with sythentics

Film strength, temp range (high end is the main criteria) and the
additive package are the key differences between 'regular' oil and
synthetics. Then the different oil OEMs and how they refine the stuff

My big block ICE won't notice dino vs synthetic, as the pumping losses
of a big block has the differences in the two types of oil lost in that

Now my 2 seater and the old 2.4L in-line six does show the difference
as the pumping losses are no where near what my Sub's big block are

There are too many attributes, studies, etc, etc, etc to discuss on
this thread. I've been studying automotive via boy racer passion since my teens

My first charge of synthetic had one quart cost as much as my hourly
wage. Where the whole 'it is good for 20,000 miles' comes from, IMHO

Today's dino is most likely better than the synthetic's back then