synthetic oil

[mzsubaru]

I'm thinking of using synthetic oil in my 2000 Outback. I've hear of the various urban legends that I shouldn't do this because it will screw up the seals in the engine, etc.

 

Someone, please give me the real story, no BS, just the facts.

[porcupine73]

I wouldn't worry about it. I have switched all three of my soobs over to synthetic at around 100k miles and it works great. Sometimes if the rear main seal is worn and there is dirt around it keeping it from leaking, synthetic oil may start to clean away these deposits and then it starts leaking. This isn't really the oil's fault; the seal was bad to begin with.

 

Also note that not all synthetic oils are created equal. Group III basestock can be advertised as synthetic in the U.S. anyway, though they are actually highly refined petroleum.

[OB99W]

The only concern I'd have is if the engine wasn't well-maintained. Sometimes when oil change intervals were too long, the PCV system not maintained, etc., there is some sludge buildup. If a large enough piece of that material breaks free due to use of a high-detergency synthetic, it could lodge in an oil passage and create problems.

 

As long as the engine has seen regular oil changes, etc., switching to a synthetic engine oil shouldn't be too risky. If you have concerns, you might try one of the synthetic blends first, and see how things are going before changing to full synthetic.

[mzsubaru]

Thanks for the info.

[1997reduxe]

I researched this a while back.

I bought my 97 Legacy at 140K. I started using I think Castrol synthetic, but then saw that Walmart had their own brand of it and was wondering as to the quality of that.

Somehow I found a forum (don't know where it is anymore) dedicated to the makeup of oils. etc.

(a quick search just showed now me there are many of these).

The basic argument seemed to center about the value of paying for synthetic versus using a high mileage oil, but i thought that it kind of defeats the purpose using high mileage since you have all that dirt etc swishing around in the engine even though the oil is still viable.

Basically also I learned that there are different grades of synthetic. Castrol i believe wasn't true synthetic, but either just adulterated regular oil or a syn/regular mix. Walmart was made by another company, but not Exxon as they seemed wont to claim at the stores to customers, but a company called Warren I believe, and not that high of quality. Mobil 1 was supposed to have been of high quality, and had certain qualities/ingredients that were good at preserving seals/engine etc (I forget now what these ingredients were).

I changed to Mobil 1, and now have 250K on the car, with absolutely no burning of oil or leakage.

One thing though--I believe you are unable to change back to regular oil once you go synthetic, and my car was I believe a fleet car before the second owner had it (I am the third), so it was probably taken pretty good care of in the beginning. It's probably been the reason it runs so well now.

[nipper]

well if you switch to synthetic, your children will grow up to be gypsies, and youll grow two more heads.

 

 

Urbane myths always have a grain of truth in them. In this case the synthetic oil does good a cleaning the residual dirt and grime from your oil system (it wasnt hurting anything, and dino was just doing its job). The grain of truth part is that some of that dirt was cloging small pores in seals. Remove that dirt, and a seal that was going to leak eventually anyway, starts leaking earlier.

 

Otherwise no harm is done. Change your PCV valve, use a high quality filter, and pop your hood at least once a month to check on everything.

 

nipper

[1997reduxe]

yeah.

that kind of reminded me of back when i did that research.

i earlier did a google search for the terms "synthetic oil seals"

and came across a few good pages just like the old ones

i'd looked at.

i remember now that i read back then that not only does oil

(any oil, of course) prevent dirt buildup and metal part wear,

but in fact preserves and infuses life, short or long, into the

seals themselves. i read that mobil 1 supposedly had a high

amount of not just detergents, but the seal helpers.

i remember now that after my ex girlfriend took her car to

walmart once to get the oil changed and they filled the engine

with so much oil (guess they couldn't read that funky stick)

that it blew at least some of the seals, or so a subaru dealer

said.

they quoted like 3000 dollars for repair.

a small shop run by an ex suby dealer mechanic said 1200.

i started putting mobil 1 in it i don't know why, and it stopped

burning oil.

probably just coincidence.

[bulwnkl]

These days conventionals have 'synthetics' blended into them, and 'synthetics' have 'conventionals' blended into them. The difference between the two is in the price tag and the marketing. Switch away and don't even think about it.

[porcupine73]

These days conventionals have 'synthetics' blended into them, and 'synthetics' have 'conventionals' blended into them. The difference between the two is in the price tag and the marketing. Switch away and don't even think about it.

That's not true unless it's a 'blend'. Group I and II basestocks are petroleum based 'dino' 'conventional' (as is group III, except it can be called synthetic in the US anyway). Group IV PAO is made from a reaction of chemicals and is truly synthetic. Group V esters and others are synthetic. If only group IV and V are used you have a nice true synthetic oil with no 'conventional' basestock in it.

[bulwnkl]

That's not true unless it's a 'blend'. Group I and II basestocks are petroleum based 'dino' 'conventional' (as is group III, except it can be called synthetic in the US anyway). Group IV PAO is made from a reaction of chemicals and is truly synthetic. Group V esters and others are synthetic. If only group IV and V are used you have a nice true synthetic oil with no 'conventional' basestock in it.

Yes, it is true. Don't be fooled into thinking that all 'synthetic blends' are labeled as such. To give just one example, it is common to make an SM/GF-4 0W- or 5W-20 with significant 'synthetic' components, but they're not labeled as a blend unless there's also a higher price tag on them.

 

Also, do not confuse base stock class number with performance level. There are companies that succeed in making bad finished products out of Group IV bases. Group III bases can outperform Group IV without all that much trouble, and they're every bit as 'truly synthetic' (meaning performance, how pure and whether synthesized or extracted) as the IVs and Vs.

 

I think most people would be very surprised as to what some of the better-quality 'conventional' oils are really made of vs. many, many of the 'synthetics' and/or 'blends.'

[2X2KOB]

Firsthand experience:

 

I switched one of the 2000 Outbacks to Mobil 1 at 148,000 miles, and the other one at about 50,000 miles, and they are both doing just fine at around 60-70,000 miles later.

 

Oil and filter change interval is 10,000, same as the air filter.

 

Go for it!