Synthetic Oil

[99gtlimited]

i've been running synthetic blend (mobil clean 7500) in my car for the last two cycles in preparation to use full synthetic. which type of oil do you all use/ which would you suggest. what is the best choice (keeping in mind performance, price, change intervals, other....)

Please let me know which you prefer and why!

[Huffer]

I like Castrol Syntec because it's usually the cheapest, and I can still buy it at Walmart in 5qt containers.

AMSOIL is reputedly the best on the list you have, but unless I was running an extremely low-tolerance, high output motor, I could spend the money elsewhere.

I ran Mobil 1 and didn't like it, the 5w30 seemed to be "thinner" than other 5w30s.

[deadlydave]

I went for the Syntec for the same reasons as huffer. Availibility and cost.

The "Best" oil is going to be Royal Purple or Amsoil. However, the "best oil for your car" may be something else entirely.

[rougeben83]

On a relatively stock motor, dino is comparable to synth, unless you plan to run 10k per oil change (suggest you change oil filters during that time though).

FWIW, I used castrol gtx on my old motor and left it at that. New motor is getting syntec upon suggestion of the installer (apparently some synthetic oils can wear down the bearings on a turbo...:shrugs:).

[SilentRacer]

^ I heard this as well about turbo motors not liking synthetic oil besides royal purple. I use mobile 1 full synthetic on this motor but on a turbo i think im going to use royal purple.

[Huffer]

It has to do with some synthetics being TOO thin... My main reason for preferring synths over dino is the resistance to burn-up.

[decke48]

heard bad things about castrol.. but i think theyve gotten better over the years. like there blend is only 6% synthetic the min. for blends. and the syntec had bad blends that it woulnt absorb much dirt making the oil sulgde. but this was 5-6 years ago. ive used mobil-1 your only paying for the name. like luicus oil. had no overall better qulitys that conventional than it lasts 10000miles before it nead to be droped. i used royal purple for a while in my 22b and rs-b over all it was the best. had a good film, absorbed dirt well and cleaned deposits. was thicker that all the other oils for the same viscosity which held better oil pressure and reduced blow bye(some but not much reduced C and N2o by 1ppm). never used redline or amsoil. but with my 129,xxx bd right now i just use conventional valvoline. no point in spending the extra $40 on the oil change. because its hard to switch a high mile engine thats used conventional all its life to a synthetic. and will not have much benifit to it.

[Airgne]

i have been using AMSOIL since 03 and have never had a problem. 25,000mile change or one year with there filter. also they have were the first to offer syn oil. been around since the 70's i believe.

[LegacyRob]

I've used Mobil 1 in my old Jeep and now in the BE. i use 5w30 in the winter and 10w30 in the summer. I might try 5w50 this summer. I i can pick it up at Walmart as well.

[AJM]

I used royal purple all last year and it did wonderful things for my ej22, but I used 10-w40 which my ej22 seems to prefur.

When my vavle springs blew ,and I was taking the head off, it was so very clean from the Royal purple and k&n filter and I was changing every 5-6k.

[rougeben83]

It has to do with some synthetics being TOO thin... My main reason for preferring synths over dino is the resistance to burn-up.

yeah, too thin an oil isn't giving you enough coating on the parts for the oil to do its job though. This hold especially true on high-strung/aggressively driven motors (like turbos) and also for a boxer design...you combine these two things and you can get spun rod bearings or other catastrophic engine failure.

Subaru actually uses something like 40w straight oil on their Group N STi's... it says so straight on their "race" quality oil that they sell.

[blackgtbeauty]

i have been using AMSOIL since 03 and have never had a problem. 25,000mile change or one year with there filter. also they have were the first to offer syn oil. been around since the 70's i believe.

Ditto, I like AMSOIL, in my engine tranny and dif.

[DLC]

Mobil 1 because White Trash Mart sells it for cheaper than is fair. 10x40 high mileage full synth.

[99gtlimited]

seems like mixed reviews so far... what's this about synthetice damaging your engine? i don't feel like this will be the case for me since i'm not even to 60K yet and have been running the slightly thinner synthetic blend for 2 cycles (i was told to do this to help the engine get used to thinner oil as to reduce the risk of any leaks or seepage). what are the risks in running a full-synthetic at this point? if any. and how much would the benefits outweigh these possible dangers? thanks for the input thus far.

[MkIII]

I now have a hard enough time finding the compatible synthetics. Before one of the local chains (GI Joe's) was purchased and promptly ruined by an out-of-state company it was not a problem.

If I can I'll get Royal Purple, failing that, AMSOil, and if all else fails; Mobil1. Which any more is likely what I'll be using.

For what it's worth. I started my Legacy on synthetics at roughly 50k miles with no obvious ill effects. The previous owner had used regular oil up until that point.

[Airgne]

i didint even do the cycle thing before using syn. i just threw it in. no problems what so ever. the only thing about syn oil is you can not use it on a new motor. if you do the rings will never seat right and you will have blowbye like a mother. im useing AMSOIL(as i said before) 10w30 high performance motor oil. [/url]

[deadlydave]

My old ej22 legacy seemed to like 10w30 as well, and dino oil only. I went to sythetic and had to switch back, it rattled like crazy and bugged the crap outta me.

[Huffer]

seems like mixed reviews so far... what's this about synthetice damaging your engine? i don't feel like this will be the case for me since i'm not even to 60K yet and have been running the slightly thinner synthetic blend for 2 cycles (i was told to do this to help the engine get used to thinner oil as to reduce the risk of any leaks or seepage). what are the risks in running a full-synthetic at this point? if any. and how much would the benefits outweigh these possible dangers? thanks for the input thus far.

Went to synth at 80k. No leaks, no problems. Ran 5w30, now running 10w40 which the engine seems to like more.

[99gtlimited]

so for a moderate climate, like here in Washington (avg temps ranging from 35-75 annually) which grade should i run? 10w-30 or 10w-40? I've been running 10w-30 for all my other cars and this one so far but is there some reason that 10w-40 works better?
thanks

[99gtlimited]

i should say Mild climate, it never really gets above 80 here during the summer, maybe two or three times, and never gets much below freezing, unless i go to Mt. Baker, but it's still well above 0 degrees F. From what i've read the 10w-40 may be a little better for the summer time and 10w-30 for the winter, is this correct to say? and if so, what are the dangers in switching off between the two (two oil changes per year, one 10w-30 the other 10w-40) to accomodate the changes in operating temp. or is it a better idea to just stick with one kind or the other year round. i know i'm asking a lot of questions i just want to get the best information from people with the most experience and the same (or similar) engine. thanks again!

[Huffer]

You can run 5w30, 10w30 or 10w40 year round. It won't matter, the thicker grades have piston-slap quietening benefits, whereas 5w30 gives greater cold start protection because it doesn't require much effort for it to be lifted from the oil pan.

Check your owners manual too.

[Airgne]

10w30 is a good all year round. also with amsoil they have the lowest freezing point of anyother syn oil. if its good enough to use on the oil feilds in alaska were its -40 almost year round its good enough for me.

[89bk]

I use Mobil 1 Truck & SUV synthetic 5W-30. If they made it thicker I would opt for that. A board member who is really into engine oil (I don't remember what forum he posted it on) said the Truck & SUV Mobil 1 is better than the standard Mobil 1 synthetic. Made heavier duty and performs better. I change it at about 5,000 miles (about every two months).

I was going to use Castrol synthetic (because I used to use the Castrol GTX on a previous Subies and they performed very well) but I saw an independent lab's test and the Castrol synthetic did not perform very well. Since the above-referenced board member uses the Truck & SUV Mobil 1, I decided to use that.

If I had a choice, I'd probably use Amsoil or Royal Purple. But $$$ is the issue so I stick with the Mobil. Besides, the Mobil synthetic outperforms the best dino oil.

In addition to changing the oil filter at every oil change, I change the air filter too. This was a tip from an automotive engineer (not automotive mechanic). who said to do that if you want your engine to last long.

[subaru_terrence]

I used to use motul 5w30 oil from dealership since it's only $10 more than mobil 1.

However, since I am going to a different dealership now, they have mobil 1 only.

Ever since I start using mobil 1, my car gets louder and the engine knocks...

Once I put in Amsoil few days ago, it is a lot more quieter now and no knock at all :D

[Airgne]

i see that everyone likes mobil1. one thing i like to do is see how long each company has been making syn oil, than look at the ones you think are the best. once you have done that look at the stats on them, them look at the warranty. not many oil companies will warranty there oil. my opinion is the better one do warranty there oil.

[Huffer]

i see that everyone likes mobil1. one thing i like to do is see how long each company has been making syn oil, than look at the ones you think are the best. once you have done that look at the stats on them, them look at the warranty. not many oil companies will warranty there oil. my opinion is the better one do warranty there oil.

Look at the poll. 40% of respondents use Mobil 1. That's hardly "everyone".

Your post would be entirely valid if you left out the first sentence, and you'd be hard pressed to find an oil company that would HONOR a warranty. With the mechanics inside an engine you'd spend a pretty penny proving that it was a certain brand of oil that failed to protect the innards.

[Airgne]

40% to me is everone because that is the highest % in this poll.

[deadlydave]

This will never end.

An independent study of taxis in NYC showed that if the oil is changed every 3k miles, it doesn't matter what oil was used.

And 40% is the largest majority. But far from everyone.

[rougeben83]

40% to me is everone because that is the highest % in this poll.

It's only 40% because mobil1 is the most readily available synthetic out of all of those.

You'd be hard pressed to find any place carry RP, Amsoil or any of the other higher-end synthetics, let alone any combination of them at any given time.

I'm going to try Rotella for the next change...10w30 for summer use. A friend who regularly tracks his 500hp STi runs the stuff and has paid to get the oil analysis done on it and it has done very well, and costs about as much as the Mobil 1 (around here in Detroit at least).

[DOOK]

mobil 1 in just about every car... motul or suzuki in the bike...

[decke48]

^rotella is very good also though its not a synthetic.. yes royal purple is hard to find a place that carrys different grades. like napa sell 5w30, 10w30, 10w40, 20w50 also carry 75w90 and 75w140 and royal ice. autozone sells 5w30 only. wal-mart sells 5w30 only. if you can find it anywere around you i recommend racer17k on ebay. good prices and free shipping (48 states) and you get it right from royal purple in tx :smile:

[AJM]

Actually, except for Castrol I'd trust anything else on that list. Redline is awesome tranny stuff!

[99gtlimited]

what's wrong with castrol??

[Huffer]

this isn't full synth, but I just discovered that Walmart is selling 5.5qt jugs of synthetic blend Valvoline oil for $12.

[decke48]

what's wrong with castrol??


heard bad things about castrol.. but i think theyve gotten better over the years. like there blend is only 6% synthetic the min. for blends. and the syntec had bad blends that it woulnt absorb much dirt making the oil sulgde. but this was 5-6 years ago.

[blackgtbeauty]

amoil synthetic in the tranny now too, so far its good. ams 5w30 for the 6th time too.

[Airgne]

what weight are you running in the tranny. im running 75w110

[99gtlimited]

what's wrong with castrol??


heard bad things about castrol.. but i think theyve gotten better over the years. like there blend is only 6% synthetic the min. for blends. and the syntec had bad blends that it woulnt absorb much dirt making the oil sulgde. but this was 5-6 years ago.

this doesn't lead me to believe that castrol is bad currently, especially since i've heard they changed their forumulas in past years. especially syntec full synthetic, which is the one i would be using.

[decke48]

^idk they were a shade company in the past. maybe theyve gotten better.

[AJM]

I think i'd buy supertech sythedic over castor...at least I know who makes it and where haha.

(Warren in case anyone wondered...)