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Discussion Starter #1
Do you guys syn oils - MOBIL 1? Do you see any difference in MPGs. Saw a show on HD Science Chanel, that proclaims you could see up to 3 MPG increase with Synthetic Oil !!! Could that be true??
 

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Do you guys syn oils - MOBIL 1? Do you see any difference in MPGs. Saw a show on HD Science Chanel, that proclaims you could see up to 3 MPG increase with Synthetic Oil !!! Could that be true??
Nope, not for me. I have a 3.0L 95 Pathfinder since new. Switched to Mobil1 5w30 around 7K miles with no noticable MPG gain. However, the engine sure is clean insde the valve train. Still recommend as I know the engine will last. I have 85K miles and still running strong without any major problem. Only had two broken manifold studs and O2 sensor replacment...
 

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Orca: I've used conventional oils with 114k miles on my 01 PF. Runs like a top, although I now have some suspension issues. She doesn't burn a drop of oil. I might experiment with a Syn Oil just to see if there is any mpg increase... Would an oil switch cause a problem??
 

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The only possible problem you may encounter is that the crankshaft seals may seep some oil.

I've been using synthetic motor oil in both of my cars and haven't noticed any improvement in MPG. The only positive issue with using Syn oil is that I change the oil now every 12,000 mi rather then every 2,000 mi with Dyno oil; cheaper for me in the long run. However I change the oil filter every 2,000 mi.
 

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I use Mobil 1 and I usually only see a difference during the first fillup. If there's any, it isn't permanent. Aside from that, I now change my oil and filter every 6,000miles.

They say when switching, seals that might have been sealed from build up may actually clean off causing leakage. When I switched, I noticed a leak and had that fixed. I like knowing what's wrong with it. Especially since she's still kicking at 178,000miles strong.
 

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Thanks Rogoman: In that case, if there's no benefit of increased mpgs, I'm not about to start to have oil leak problems. I'll stick with the conventionals: Penzoil, etc...
 

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What if it was proven that your vehicle could keep the stock MPGs while everyone else loses MPGs?
 

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90seven: I guess with all OTHER things being equal [new spark plugs, using Premiuim gas, etc] , you should generally get the "stock" MPGs, right? So, will using Synthetic Oil bring UP the mpgs. After what has been said about developing potential oil leaks from seals, I don't think I'll try it. I'll wrestle with some more. Metro272, your thoughts??
 

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in my experience there's no *significant* increase in mpgs using synthetic oil. the cost benefit imho is longer durations between oil changes, only if you do it yourself though, if you pay a shop for synthetic the upcharge negates any savings.
 

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If there is an increase it is minimal. I switched my 97 to Mobil1 as soon as I got it and I switched my 01 over as well. I prefer Mobil1 over all the other easily accessible oils, Royal Purple and Amsoil are the only other two I would use.

And Almatti, I would switch your Pathfinder over to synthetic next oil change. VQ35's are known to get sludge buildup in one of the heads and burn oil. Synthetic doesn't sludge like dino oil and will remove sludge over use.

And I change my synthetic every 5k miles or 6 months, I use the Mobil1 extended performance oil filter and change it at the same time.
 

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Just my 2 cents worth

I know a very good Porsche mechanic who says (and I've heard this elsewhere) that synthetic oils will cause seals to expand, thereby increasing the sealing ability. However, once those seals have expanded, switching back to Dino oil will cause them to shrink again and definitely cause leaks. so the warning is, once you go synth, you can't go back to Dino (without considerable consequences and expense).
 

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i switch the to synthetic oil last month and have seen a difference in my gas mileage. It has changed for the better there is an increase.
 

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i switch the to synthetic oil last month and have seen a difference in my gas mileage. It has changed for the better there is an increase.
Yes, there's an increase but is it enough to justify the much higher cost of synth? I don't think so. I use synth but for many reasons, not mpg increase alone.

If you saw more than a .5 mpg gain on synth I'd bet there are other factors at play - like warmer air temps or something. I've tried everything i know and all those things combined only raised my mpg less than 2 mpgs. I'd say the two things that helped me the most were careful driving (slowing down, coasting to stops, staying off the brake, avoiding jack-rabbitt starts, etc.) and partially blocking the front grill when the air temp was low over the winter.

I am now experimenting with different octanes and gas brands. Early indications are that my Pathy does better with higher octane gas but again it does not seem to make up for the additional cost per gal. I do think that Sunoco gas does better (than lower off-brands) but don't have enough to go on to say that for sure yet. I also want to remove the cross-bars on from the roof rack but i can't get the ***** things off!

FWIW i am consistently in the mid-18 mpg range with mostly rural driving.
 

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Panzer,

Back in the olden days there were 2 kinds of synthetic oils, one expanded the seals and one shrunk them. I don't think you will see that so much with the current major brands.

However, some of the 'Extended Life' oils do advertise that they soften the seals. I'm using Valvoline Max-Life in my truck and it seems to have cleaned up all the little leaks I had.
 

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Discussion Starter #16
Panzer,

Back in the olden days there were 2 kinds of synthetic oils, one expanded the seals and one shrunk them. I don't think you will see that so much with the current major brands.

However, some of the 'Extended Life' oils do advertise that they soften the seals. I'm using Valvoline Max-Life in my truck and it seems to have cleaned up all the little leaks I had.
Great Info Guys, Thanks. Lots of Food for thought on whether to switch to Syn Oils. You know, in the NY metro area, "winter Blends' of gas is used. That seems to lower MPGs. I think there is more ethanol added, and a cold engine difinetely burns much richer until full warm up. I'm getting about 12 MPGs in city driving, not suburban driving, and max highway with feathering the throttle and no real traffic issues, {and maybe some help from "tailwinds"} I'll see 18.5 MPGs max. 2001 PF 4wd LE 114k miles on the clock using regular oil or a Blended oil (at least that's what Firestone tells me).
 

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Been using Mobil 1 for years, recently switched front & rear diff to Mobil 1 as well. No noticeable difference in MPG.

I have been doing alot of reading lately and am starting to think Amsoil may be the way to go. Anyone have any thoughts? Not much of a difference in price but it isnt carried in stores, its dealers or mail order.
 

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It's probably hard for me to tell the difference. When I switched to synthetic, I also added on new wheels and larger tires. MPGs had stayed the same, so as far as what has been recorded, it hasn't changed. I do know that my odometer is off about 10%. It shows I go .9 miles when I actually just traveled 1 full mile.

I also just installed Manual Hubs on the Pathy a week ago, I'll let you know how much of a difference it makes when I calculate the at the next fillup. Maybe these hubs will do more justice than switching to synthetic oil.
 
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