Castrol Syntec 10W-40

[vvk]

You have one chance to convince me NOT to put Castrol Syntec 10W-40 in my engine.

I have a 1998 Subaru Impreza 2.5RS with almost 80k miles. The manual allows for a range of viscosities. I would like to use 10W-40 this summer. I would also prefer the oil to have ACEA A3 rating. Out of the oil available to me locally I can only find Castrol Syntec, Castrol Synthetic Blend and Valvoline Durablend to fit these requirements.

I looked at Castrol Synthetic Blend and it seems to be a little too thick for my liking. Syntec, on the other hand, is on the thin side of 40 weight, which is what I prefer. The car has been run on Mobil 1 5W-30 since new.

I almost decided to try Castrol Syntec 10W-40. I knw it's Group III. But it's cheaper than Mobil 1, so the price seems to reflect the cheaper base stock. Well, actually with the 5 quart canisters at my local WalMart Mobil 1 is slightly cheaper. But it is not available in 10W-40. 15W-50 is way too thick to my liking and 10W-30 does not have ACEA A3 rating.

Maybe I should just use Mobil 1 10W-30? Or maybe I should use a quality non-synthetic, such as Motorcraft 10W-40. I use it in my other Impreza and it seems to like it a lot.

What do you say? Syntec, Mobil 1 or just a quality non-synthetic? I don't mind changing it at 3k miles. For winter I plan to use Castrol SLX 0W-30.

 

[G-MAN]

If it were mine, I'd stick with the Mobil 1, or maybe switch to the German Syntec 0w30. As far as "protection," I can see absolutely no advantage to using Syntec 10w40 over either of these two oils for summer driving.

 

[Patman]

I agree, go with the Syntec 0w30 since it's probably roughly the same price, but is definitely a full synthetic (the German version that is)

And the 0w30 is almost a 0w40 anyways, and that Syntec 10w40 would turn into 10w30 pretty rapidly most likely. So after 2000 miles in your engine the 0w30 would end up having a thicker viscosity at 100c.

If you were planning on using this oil in the winter, you might as well use it in the summer too.

 

[Dr. T]

Go for it. Better yet, give us a UOA when you're finished with it. You may even prefer it over the M-1 have. Certainly won't miss the consumption (if you have any)...

 

[vvk]

quote:

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Originally posted by Dr. T:
Go for it. Better yet, give us a UOA when you're finished with it. You may even prefer it over the M-1 have. Certainly won't miss the consumption (if you have any)...

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That's exactly the thing. I do, and it seems to have something to do with PCV system. Some day I will fix it but at this point I just want to get rid of consumption. I want to try something a little thicker, especially since the owner's manual allows for as much as 20W-50. I am struggling between using Motorcraft 10W-40 for 3 months or Syntec 10W-40 for maybe a little longer, maybe not. I usually go 6 month between changes with Mobil 1 and plan to do the same with Castrol SLX when I put it in for the winter. I am convinced at this point that Mobil 1 5W-30 will eventually cause consumption if used for a long time. Not so sure about 10W-30. 5W-30 seems to thin out a lot and that is what causes consumption, eventually. Mobil 1 10W-30 seems to be much better in this regard.

It is tempting to put Castrol SLX in it now but I only have 6 liters of it and who knows when I will be able to buy more, since local AutoZone store does not carry it yet. They have about 20 bottles of old non-SLX 0W-30 on the shelf and I am guessing that will last a very long time there

And who know when I will be in Toronto next time, with SARS and all...

So I have to save my SLX for the winter...

 

[slickracer]

I would use Mobil 1 10w-30. It may not be the absolute best, but UOA's as a rule have been very good. And it is available everywhere.

 

[YZF150]

For Pete's sake quit worrying about SARS. Sheesh.

Use the 0w-30 now.

And take a nice drive in the beautiful Fall colors across the frontier and get some more for the Winter.

 

[Jimbo]

Go for it and please post a UOA. It is one of the very few ACEA A3 synthetics that I can find OTC. BMW North America discontinued the 5W-40 Syntec, so the 10W-40 may be a good replacement. I know that the 0W-30 has a lot of fans here, but the German stuff is not stocked everywhere and is too thin for some applications.

 

[nicrfe1370]

1) As far as grade, anything from 0W-30 to 20W-50 has good UOA's in Subaru engines.
2) If you want peak performance at all times and long engine life, stick with synthetic. If you want economically priced oil, go with a mineral oil. If you want a combination of the two, get a blend.
3) I am certain the syntec will work fine at least for regular drain intervals. But since Mobil 1 is cheaper that Syntec where I live, Syntec would be the big loser in my pick.
4) Do at least 1 or 2 oil analyses with whatever you chose to see how the oil works in your car, and how long is reasonable to run it.
5) Bottom line; Mobil 1 10W-30, 15W-50, or a mix of the two would be my choice.

My opinion is based on this:
http://home.earthlink.net/~jabrande/oilanalysis/SubaruTrend.xls

 

[68redlines73]

Well, according to Kelley Blue Book, you're car has a trade-in value of about $7300, assuming it's in excellent condition. Thus, I'd suggest just going for something simple like Chevron Supreme 10W-30 (which this board tends to approve in the 'dino' category) at 3000 mile change intervals, skipping the UOA and enjoying all of the time and money you'll save.