Mix or 5W-40

[melayout]

I've got a 2005 Subaru Legacy GT (2.5L Turbo 13.5PSI) and I'm not liking the oil consumption with Mobil 1 5/10W-30.

I wanted to try GC with a 12 cst right between most 5/10W-30 and 5/10W-40 oils, but my service advisor said, "It's too thin" and I know he is wrong but I won't go there unless I can get his or Subaru of America's approval in writing.

My other 2 options are :

1. Since I need 5 quarts, I can mix 2.5Qs of 5W-30 and 2.5Qs of 5W-40 to get something similiar to GC's viscosity

2. or just go for a 5W-40 oil

I want a full synthetic and I'm looking at Mobil 1 or Castrol Syntec since each are readily available in 5W-30 and 5W-40 weights.

The 5W-40 Castrol available at my local Autozone is made in Belgium, but I haven't looked where the 5W-30 is made.

Does Castrol's 5W-30/40 have similar cleaning and TBN retention as Mobil 1?

Should I go for the mix or go to just 5W-40 ?

Castrol or Mobil 1?

I just want an oil with GC final viscocity(12 cst@100deg, a thick 30 weight), a starting viscocity of a 5 weight, fully synthetic, has good cleaning and TBN retention and is readily available(Off the Shelf).

 

[Mitch Alsup]

How many miles on this motor? It is fairly common for new engines to use a little oil before they seal up tight.

How hard are you running this motor? It is common for high performance engines to consume some oil when running the snot out of them (like HPDEs), and yet consume no oil whatsoever under nore traffic friendly driving conditions.

If I were you, and given that you are using the car "traffic friendly" and that it has more than 5,000 miles on it; I would simply jump to a 5W-40 oil or do a search for an oil with an HTHS number above 3.6 from the 5W-30 selections.

 

[melayout]

My first and recent UOA : http://theoildrop.server101.com/ubb/ultimatebb.php?ubb=get_topic;f=3;t=002578#000000

 

[melayout]

I have 29K miles on the car right now.

As expected the consumption went up significantly in North Carolina 90-100F weather.

I can't get myself to take it easy to see if no oil is consumed in normal/grannie driving, so I just have to keep trying different oils till I'm comfortable with the consumption.

It consumed 2-3 quarts in 4000 miles and according to Subaru of America 1quart/1000miles is within spec.

But again, I drive the snot(oil) out of the car.

 

[melayout]

Also, it is my daily driver and a one way drive to work in 10-14 miles with 70% highway.

One more thing, is Mobil 1 Truck & SUV 5W-40 warrantied by Mobil 1 for turbocharged gasoline engines, since I didn't find that exact wording like other weights on their site?

 

[reyjay1]

quote:

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Originally posted by melayout:
I've got a 2005 Subaru Legacy GT (2.5L Turbo 13.5PSI) and I'm not liking the oil consumption with Mobil 1 5/10W-30.

I wanted to try GC with a 12 cst right between most 5/10W-30 and 5/10W-40 oils, but my service advisor said, "It's too thin" and I know he is wrong but I won't go there unless I can get his or Subaru of America's approval in writing.

My other 2 options are :

1. Since I need 5 quarts, I can mix 2.5Qs of 5W-30 and 2.5Qs of 5W-40 to get something similiar to GC's viscosity

2. or just go for a 5W-40 oil

I want a full synthetic and I'm looking at Mobil 1 or Castrol Syntec since each are readily available in 5W-30 and 5W-40 weights.

The 5W-40 Castrol available at my local Autozone is made in Belgium, but I haven't looked where the 5W-30 is made.

Does Castrol's 5W-30/40 have similar cleaning and TBN retention as Mobil 1?

Should I go for the mix or go to just 5W-40 ?

Castrol or Mobil 1?

I just want an oil with GC final viscocity(12 cst@100deg, a thick 30 weight), a starting viscocity of a 5 weight, fully synthetic, has good cleaning and TBN retention and is readily available(Off the Shelf).

---

The German Castrol may be a better oil than the Mobil 1. Syntec in 5-30 or 5-40 is a high priced GIII blend with probably some GV. Many consider this not a true syn.
Mobil 1 is the benchmark synthetic.
Castrol 5-30 is most likely blended in the US.
Mobil 1 5-40 most likely wont be consumed any faster than the 5-30, and maybe less, slight possibility maybe more.
I think you are going to have to experiment and find which it likes best.
Your service advisor cannot tell which oil is in your car unless you tell him, and I doubt they will be doing any analysis of the oil.

Try the 5-40 and if you don't like the fuel consumption, try the mix.
Or just bite the bullet and try the GC, or valvoline maxlife, or Pennzoil Platinum, or do an AutoRx treatment and see if consumption decreases. Or Rotella T 5-40. Or Premium Blue Extreme 5-40.

Does Castrol's 5W-30/40 have similar cleaning and TBN retention as Mobil 1?
Cleaning- doubtfull , TBN retention- probably not.

Check your PCV valve or replace.

 

[surfstar]

An alternative to the syntech would be Walmart's Supertech 10w30 which is ACEA A3 rated. Might hold up a little better against burning. Pennzoil Platinum and Quaker State's new Q Synthetic are supposedly A3 rated also for 10w30. The Q can be had for $2.99/qt after rebate and the Supertech is always under $3/qt at Walmart.

 

[Pablo]

I would run Amsoil 5W-40 AFL.

 

[melayout]

Is Pennzoil Platinum a true full synthetic ?

Edit: Scratch that, the 10W-30 weight is not A3 rated.

 

[AndyH]

quote:

---

Originally posted by reyjay1:

quote:

---

Originally posted by melayout:
I wanted to try GC with a 12 cst right between most 5/10W-30 and 5/10W-40 oils, but my service advisor said, "It's too thin" and I know he is wrong but I won't go there unless I can get his or Subaru of America's approval in writing.

---

Your service advisor cannot tell which oil is in your car unless you tell him, and I doubt they will be doing any analysis of the oil.

---

Agreed, I'd give GC a try.

melayout: If your service advisor won't "approve" of GC, what makes you think they'd "approve" of you mixing two different oils together? Don't sweat it man, just give GC a try and see what happens with your consumption.