Subaru Impreza WRX synth recommendation?

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Nov 24, 2002
Dear all, Enjoying the forum. Saw a few Subie owners' archived posts but wanted specific info: Vehicle is '02 US spec Impreza WRX, 2.0L turbo, ~4.5L oil sump, driven daily mostly on motorways, usually distances over 20 miles. Ambient temps range from 10C to 25C in "winter" and 20C to 40C in summer. Speeds are typically 65 to 85 mph, 2700 to 3500 rpm. Redlining and boosting in low gears isn't frequent but it's not completely unheard of... Moderately to mid-level dusty, low humidity environment (I live near farms). Air filter is Subaru, intake is stock, no modifications to vehicle at all. Oil filters are works Subaru from the dealer. 7,000 miles on odometer. First change at 3,000, second at 6,500, both dealer's dino oil. I'd like to switch to synth at the earliest advisable point. What mileage should I switch at? Archived posts suggest my motor breaks in over a rather extended interval. Is 10K OK for me? Or wait to 15/20/something else? What synth oil for me? Mobil 1's rep said "use our 5W-30 year round" but in the same breath said "we use no moly in our oils" which got me thinking, considering the analyses and messages posted here... Still, Mobil 1 is attractive since I can get small lots of SL stuff OTC, with a dated receipt for warranty puproses, and it's genuinely a good synth oil. Any turbo'd 4 owners or WRXers specifically running M1 SL 5W-30 care to share info? How about 0W-40, 10W-30, or 0W-30 for my application? Better/worse for wear? (Manual prefers 5W-30 but also lists 10W-30, 10W-40). I'd like 4,000 mile drain intervals (dust concerns and turbo temps) and my goal is longevity, not fuel economy or even power. 4K drains shouldn't be a problem with a normally aspirated commuter car and any SL oil theoretically, but my WRX isn't normally aspirated and isn't always strictly a commuter car - fellow owners will know what I mean. Looking forward to any info, thanks! [Smile]
Well your best bet is to try a few things and have each analysed. I'm not sure what would be best in a turbo application, but I'm also interested in this thread since I might soon own a WRX too [Smile] (love em). I'm sure a 10W-30 weight will be a very good choice for you - what part of the country are you in? The oil brands to choose from are immense, but I'd say a Schaeffer's Blend or Redline might be in your best interest. Most people here have had fine results with 10W-30 Mobil 1 too! Its hard to say [Smile] Hopefully some other people will chime in soon.
Rallyfan: You post your temps in C so I guess you're not in the US....Australia? I'm not sure if the formulation for M1 differs in your local but M1 is now using about 80ppm Moly in their US formulated oils. Schaeffer's would be a good choice but may be hard to get. Any of the premium synth oils should hold up well past 4,000mi. How many miles do you put on per year. M1, Redline, Amsoil, Schaeffer's, etc. will perform nicely changed every 6mo/5-7k mi on the conservative side. In dusty conditions I would go with a foam air filter. I've been using Amsoil air filter on my cars getting near zero ppm on silicon each oil analysis.
Located in CA, USA. Looking at Redline's site, they state "Satisfies warranty requirements of API SH/SG/SF/CE/CD/CC" but curiously no SL. I know this isn't an issue to anyone except a constipated warranty claims adjuster ten years down the line, but that's exactly who I'm interested in theoretically fending off. So Redline seems out of contention. Shaeffer's I've never tried, the numbers look fantastic, but availability in small lots becomes an issue - I want those receipts for my files every few months. It's ironic how a lubrication question has all these caveats that have little to do with actual lubrication! I'm contemplating some Mobil 1 weight, wondering which. As for the WRX, I think you'll like it. It's a practical car that's very capable despite a nondescript appearance, and can maintain ridiculous speeds in all sorts of weather over any terrain short of tank proving grounds. My wife drives it to work, I do too; I also (very rarely) drive it for fun in rather remote areas and it's very composed. One snafu is that - due to very high traction and quite responsive motor - mistakes tend to happen at rather elevated speeds, so things progress quickly and it's easy to run out of real estate... I can definitely see why it's got a decade-long cult following worldwide. I was thinking 10W-30 too, then saw all the great data from the 5W-30 and thought "best to just ask" [Big Grin] Dominic and mormit, thanks very much for the responses. One posted as I was reading the other. I'm hoping for 15K per year but may exceed this. Never really caught on to Fahrenheit temps, kept my old thermometers, also suspected C temps might make sense to people in markets where the motor isn't new too (hoping to get lots of info). I think I'll be looking closely at any wear figures for M1 5W-30 vs. 10W-30 I can find and pick one of the two initially, perhaps at 10K and until 14K, at which point I'll do an analysis. Meanwhile I'm hoping 0W-30 and -40 data will be in for a turbo 4 motor, if not mine specifically. I'll look into the foam air filter too. Thanks again and cheers! [ November 25, 2002, 09:37 PM: Message edited by: Rallyfan ]
Rallyfan, as an OT post, I went to the Rally of Tall Pines in Bancroft, ON, and both the leading Subaru WRXs of Tom McGeer and Patrick Richard used Motul 5W-50 in their cars (I asked the mechanics).
Ferrari, Motul's stuff is popular and rally folks run it a lot - even the wide spread xW-50 stuff in a Group N car. I'd looked around for it but it's also a mail order affair for me, too bad. Another thought I had is strolling over to a BMW dealer and seeing what they have in a full synth ACEA A3/B3 5W-30, provided it has the all-important API SL star on it to keep Subaru of America happy. Then the thought of simply going to Walmart once every few months and keeping life simple struck me, and I'm leaning that way. Things are getting complicated, too many choices!
With a car that's a turbo-->= never less than 40 weight oil. A car that driven only in warm climates -->=also never less than a 40 weight oil. Since both those conditions apply, which by themselves would have sufficed for a 40 weight recommendation, I would say a minimum of a full syn 40 weight. Any number of group III or better group IV synthetic oils in xw-40, will be great in your application. Or a 50 weight might also be an excellent choice, well given your conditions even in a younger engine such as yours. I would probably run a 10w-40 Amsoil, a 10w40 Schaeffer (yes fellas I am starting to get on the moly bandwagon too) a 15w-50 MOBIL1. Fred... [Smile]
As Palmerwind said, everything points to a 40wt if your manual allows. What is the maximum recommended wt for your car. Mobil looks like the best as it is API certified (knocks out Redline and Amsoil) and easy to find OTC (knocks out Schaeffer's). That said I used Amsoil XL7500 in my turbo S40 through the summer in >100degF weather. Did high speed, long distance driving (90+mph, 12hr) with very good wear numbers. Oil was thinning at 3,600mi so I changed it out. This was with Amsoil's all PAO XL formulation so I don't know how well the new PAO/group III will do. XL is Amsoil's API certified but low tier formulation. Meets OEM specs for oil requirements but lowest Amsoil product.
Hey rallyfan, I'm a follower of WRC as well. [Off Topic!] I figured at the beginning of the year that Tommi Makkinen would be unbeatable in the Soob. I just figuired that the Soob would one of the more reliable cars ... much more reliable than those silly French cars ... the Peugeots. [Wink] Little did I know. I wonder if Team Soob's problem is that they are using too many off-the-shelf components in their rally cars? [I dont know] I'm staying away from AWD in my daily driver for the time being. Don't want the added expense and fuel consumption from turning that extra machinery. [Wink] Anyway, with the weights your manual lists, I think the safest bet would be 10W30. The 5W30 will be less shear and thermally stable ... a definite concern in a turbocharged engine. The only thing it really gives you is a little better cold weather pumpability (no issue in CA). I don't see the point in using it. If your analysis look marginal, I'd consider 10W40 ... but give 10W30 a chance first. [Smile] For some fairly sound reasons, you seem to be leaning towards Mobil 1. I'd advise you that there are some very flexible Schaeffer dealers in California, however. I've heard other guys talking about putting together orders. You might even find that a dealer is within a reasonable driving distance. Also, with the Soob's AWD system, I suggest you pay special attention to your tranny lubricants. And for that, I'd suggest whatever product Red Line has that most closely matches the requirements listed in your manual and closely follow the change intervals. Price considerations be damned. Use the best stuff available for this application ... period! --- Bror Jace
I'd run the Amsoil 10w-40 synthetic, which is ACEA A3/B3 rated and has a high temp/high shear viscosity of 4.2 Cp and a Noack of 6.6%. This was Amsoils' recommendation when I asked them what oil they recommended for the newer Mercedes engines with the flexible service schedules. This oil uses a CI-4/SL additive chemistry and has a TBN of approx 12.5, so I think that 4000 mile drains will be easy ....Test it a couple of times and I believe you'll see there is plenty of margin. Think of this oil as a gas engine version of Mobil Delvac 1 - that's the best comparison I can make.
Terrific of you all to respond, thanks so much! Palmerwmd, thanks for the tips, will look into it! Mormit, 10W-50 is the maximum listed in the owner's manual, and such an oil in a A3/B3 version would be a dream lubricant! Maybe one day... Bror, I've followed the WRC since 1982, love it. Subaru has almost always had an Audi-like concept of keeping production cars and works rally cars as closely related as possible (yet they pushed for the rule change away from Group A toward WRC - maybe because they already had a suitable platform?). On his day, Tommi is still one of the top 5 or 10 fastest guys on the planet. Don't know what went wrong this year. Peugeot is a serious opponent. After all, they won titles in their first two years out back in the 80s. It's not that the Subaru is too big; Peugeot is moving to a larger chassis anyway. Maybe teething problems, bad luck, lack of specialist crews to supplement the regulars at specific events (a la Panizzi), and not enough time for everyoe to adapt? Looking forward to '03. Tooslick, thanks. I'm beginning to think A3/B3 specs are a godsend.
Motul makes a fully-synthetic, ester-based 0w-40, 5w-40, 10w-40, 10w-50 and 15w-60. They use mostly esters and almost no viscosity improvers.
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