Synthetic motor oil? Should I?

[guy123]

I know this question has been raised time and time again, so I appologize ahead of time. I'm trying to accumulate some of your experiences all in one place. I have a 96 Legacy L wagon, auto tranny, 108,000 miles, that was recently leaking oil until i replaced a few seals. All seems well now. I must admit I'm a little MPG crazy, so hence my questions despite my car's condition...

 

1. Can I run a synthetic blend or a full synthetic oil without major leaking problems?

 

2. Are there certain brands that contain additives to prevent leaks?

 

3. And are there any significant MPG improvements with syn motor oil?

 

4. A bit beside the topic- is there a good oil additive I can use that would clean out the sludge and varnish buildup from running dino oil for years, and perhaps condition and revitalize my seals? would this just be a stop leak? And would a good synthetic oil do this for me?

 

I will add that I used Castrol Syntec Blend in my Toyota 4runner (215k miles) and developed leaks. I changed back to dino oil and within one oil change the leaks slowed or stopped, so I'm aprehensive about synthetic in an aged engine. Still, my quest for better MPG keeps steering me to this option. Thanks for your input!

[86subaru]

i used amsoil , and yes it did leak more , + mobil 1 oil filters , i always let the oil go down alittle and try and add 1qt of tranny fluid ,drive it like 200-300 miles and change the oil/filter , i use x1r stuff and i have seen it work [ oil additive ] just my opinion

[PAezb]

If your main goal, as you state, is the improvement of MPG, my experience with synthetic (Mobil 1) in my 96 OBW (194K) is that I realize very little improvement in MPG over Dino. Given the cost of synthetic over dino, it's a loss from an economic standpoint - synthetic blend would be more of a wash or slighty ahead in this regards.

 

The advantages are stable viscosity at temperture extremes (less wear at startups, epecially in northern winter months), and I judged the synthetic to look cleaner than dino at oil changes (5K intervals). An argument could be made that you can run on the synthetic longer between oil changes due to it's ability to reduce wear and suspend contaminants better.

 

And yes, synthetics tend to leak more, especially if you have a lot of miles on the engine. Now, for my 96', given it's age and miles, I just put Wally World oil (SuperTech 10w-30) or the Fleet Farm brand (Resolute 10W -30) in her. For $5 - $6.50 for the 5 quarts containers, doing the oil changes at 5K with a fresh filter, the car has done just fine on dino.

 

That said, I do run Mobil 1 in my 05 OBW.

 

Adding to what 86subaru stated, I've done the "old school" method of adding a quart of transmission fluid to the crank case (making sure not to overfill) and running a couple of hundred miles before an oil change, and I think it does work well (normally once a year). Talking with older mechanics, they've said that years ago it was common to fille the crankcase up entirely with ATF, run the engine a short time, then dump and fill with regular oil. Now of course, there are many additives available to do the same thing.

 

Consider using Seafoam in the crankcase - definitely a thumbs up here...

[Subie Gal]

i wouldnt put full synth in a 1996

high mileage - worn engine

 

something like mobil 1 will find each and every leak

may cause you more harm than good

 

 

subaru uses a castrol synth blend @ their dealerships

i'd recommend something along those lines

 

Jamie

[Ranger83]

I used Castrol High Mileage with good results. And while I'm using Mobil I in all my new vehicles, it leaked in my 97 OBW. The best MPG tool is your right foot.....

[Buick350X]

I ran some Rotella through Moms Sub and my Firebird.

It was a mistake in the Firebird.

Rotella is some good oil with heavy duty cleaning agents like ATF.[Why folks do the ATF trick for it cleaning agents. ] Lots of motor builder swear by it but they are build old muscle iron.

 

But my 220,000 mile Firebird that had a constant 40 psi of oil for 7 years dropped to 20psi. The rotella cleaned to well.

 

 

Never used seafoam in oil but its is monster hugh in the bike world. First thing ya do if ya got a funky runner. Most times a bottle of that run through the gas will cure all sitting problems.

[Buick350X]

Should note the Rotella did it magix in about 200 miles in my Firebird.

It was change back to reg 20-50 like before soon as I noticed with no changes. Even added some lucas to make it super thick, no change. Rotella is 15-40 only.

[Scoobaroo]

I just put Wally World oil (SuperTech 10w-30)

 

 

SuperTech oil is the nectaur of the Gods............and for only around a buck a quart.

Toss in a SuperTech oil filter and you have around an $8 driveway oil change.

 

White trash livin' at its finest!

 

Don't forget to recycle that old oil!

[fastwgn286]

yes, always recycle the oil. throwing it out into the neighbors yard is not ideal (from their perspective, at least)

 

i dunno, but i've ran supertech in my car previously and it wore too quickly. worn out at 2500 miles. maybe the oil or that crap fram filter i had on there :banghead:

[Buick350X]

yes, always recycle the oil. throwing it out into the neighbors yard is not ideal (from their perspective, at least)

 

i dunno, but i've ran supertech in my car previously and it wore too quickly. worn out at 2500 miles. maybe the oil or that crap fram filter i had on there :banghead:

 

 

Thats the catch with cheap dino oil. Nothing wrong with it but ya should change it more often.

[fastwgn286]

yeah, i know. buy cheap, get cheap.... but things are a changin' for the rally pup....

[guy123]

Interesting. Thanks for the info. So a quart of ATF run with the motor oil for a few hundred miles will get my seals in good condition? Are those temporary results or will the condition of the seals stay improved for a few oil changes? Thanks.

[Scoobaroo]

i dunno, but i've ran supertech in my car previously and it wore too quickly. worn out at 2500 miles. maybe the oil or that crap fram filter i had on there :banghead:

 

Did you have an analysis done? I'd be interested in seeing the numbers if you did. The "SM" standard is very tough to meet. I run 5k intervals with ST 5w30 in '02 Outback with a SuperTech filter. No problems so far. Do you do a lot of short trips? Short trips will tear up engine oil pretty fast.

 

Some used oil analysis of Supertech that I've seen have been no better or worse than any other oil.

[fastwgn286]

no analysis, just looking at the stuff at the end of the dipstick, gas mileage, etc. the 10w30 i had in there went from a nice honey-ish hue to a thick dark brown in about 2500 miles. gas mileage from 30 on a highway trip (not scientifically accurate, i know, no butting heads here) to about 26 on the return trip. i dunno if my headgaskets caused some of it or the frappy filter, but it did happen on the first oil change and the subsequent ones. i think i'll run a syn blend to clean the engine a little and see if anything changes....

[edrach]

no analysis, just looking at the stuff at the end of the dipstick, gas mileage, etc. the 10w30 i had in there went from a nice honey-ish hue to a thick dark brown in about 2500 miles.

Some comments here from a guy I knew who did oil analysis (limited to dino oil since synth wasn't available then:rolleyes: ). Basic oil all starts as 30 weight; after adding all kinds of ingredients, it comes out as 10W-30 with the API engineers seal of approval for meeting various minimum standards. The first time you start your engine after the oil change, those ingredients start to go away and at 3000 miles after the oil change, you are back to basic 30 weight oil and whatever other grunge your filter didn't catch. From that I took the following approach: I change my oil and filter every 2000 miles and generally use whatever oil I find on sale and buy it by the case. Over the long haul, the cost of savings buying "cheap" oil exceed whatever savings are gained by lower gas consumption. Over the last 40 years, most of the cars we've owned lasted to 250,000 miles (baring an external disaster like an auto accident) and were still running when we sold them. The one exception was our current '91 Legacy wagon. I bought it with 93K on it, and at 100K switched to a full synthetic with oil changes at 5K (I got tired of changing the oil every three weeks). I didn't have any problems with leakage, but did develop a severe case of "blow-by" (rings?) at 155K which required an engine swap. Whether that was the fault of the oil or not is immaterial. From a purely economic consideration the most cost effective way is to do oil changes often with the least expensive dino oil that meets API specifications. There are no long term savings in gas consumption or cost repairs that will justify the cost of going to a synth oil.

[fastwgn286]

Some comments here from a guy I knew who did oil analysis (limited to dino oil since synth wasn't available then:rolleyes: ). Basic oil all starts as 30 weight; after adding all kinds of ingredients, it comes out as 10W-30 with the API engineers seal of approval for meeting various minimum standards. The first time you start your engine after the oil change, those ingredients start to go away and at 3000 miles after the oil change, you are back to basic 30 weight oil and whatever other grunge your filter didn't catch. From that I took the following approach: I change my oil and filter every 2000 miles and generally use whatever oil I find on sale and buy it by the case. Over the long haul, the cost of savings buying "cheap" oil exceed whatever savings are gained by lower gas consumption. Over the last 40 years, most of the cars we've owned lasted to 250,000 miles (baring an external disaster like an auto accident) and were still running when we sold them. The one exception was our current '91 Legacy wagon. I bought it with 93K on it, and at 100K switched to a full synthetic with oil changes at 5K (I got tired of changing the oil every three weeks). I didn't have any problems with leakage, but did develop a severe case of "blow-by" (rings?) at 155K which required an engine swap. Whether that was the fault of the oil or not is immaterial. From a purely economic consideration the most cost effective way is to do oil changes often with the least expensive dino oil that meets API specifications. There are no long term savings in gas consumption or cost repairs that will justify the cost of going to a synth oil.

 

cool. that gives me a better understanding on why it does that.

 

the problem with full synth oils in older cars is that they are too expensive and can clean away too much grime and sludge in the engine and expose leaks in worn gaskets, which should be replaced and fixed anyways. since its older, its probably not too economically smart to replace every leaky gasket, so leave the grime and the gasket doesn't leak. viola! i know my engine needs a little cleaning, not sure if i'll try a blend or seafoam, but i got lots of time before my next change (and other car parts to change under there anyways)....