Mix 'M1 5W50' and 'Shell Helix Ultra 5W40'

[zoli]

Hi Guys,

My current fill is M15W50, but oil change time is coming. There are 2 quarts Shell left on the shelf and I intend to buy 2 quarts M1 to blend a still 'thick' oil to my '98 SAAB.
I can't see any risk with it.

Any opinion, please?

 

[zoli]

So, seems to me this is not a big issue...

 

[r34dy2fly]

I'm sure a lot of people here will recommend you not mix two different brands together as they have different add packs that might not play well with each other.

I wouldn't do it.

 

[zoli]

Thx for your input!
BTW, I can't see any huge problem with the mix: synthetic oils, API group III+, probably different add-pack, but ACEA A3 qualified both.

 

[r34dy2fly]

But you're taking away how the oil was intended to be used. When Mobil created their formula, they had it made for a specific purpose. SOPUS is the same way. You mix the two, I'm sure you won't have catastrophic issues but I don't think it would work as intended.

 

[zoli]

Yes, I agree with you.
My 'only' problem is the extremely high oil prices are here. That's why I'm thinking on to mix the rest oils from the shelf.
Actually, 5 quarts M1 5W50 is on SALE here: USD 59.

 

[stormy]

59USD for a 5 Liter Jug is about 9€ per Liter.
It cost´s 9,8€ per Liter here, depending on how much you order. Cheapest price where I order it is 9,60€.

Instead of Mixing I would bump the OCI up from 5k to 6k or even 7k

Depending on driving style and so on maybe even 8k

But the shortest OCI with that oil would be 6k = 10tkm...

Still have 8,5 Literes here, might just put it back in my 1.8T. And go from 6k up to 7 ore 8k. The oil should be able to handle it:

http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=2243420#Post2243420

 

[CATERHAM]

The compatibility requirements of all PCMOs are very stringent so you need not be concerned.
Mix away.

 

[dparm]

Optimal? No.

Reason for concern? No.

 

[CATERHAM]

An inappropriate oil choice of one brand may be no where near "optimal" for a give application.
While a blend of different brands could be more "optimal" if certain attributes of the final blend are brought closer to what is most suitable for the given application.

The obvious first question is why the OP feels the need to run the heavier than spec' 50wt oil in the first place?

 

[zoli]

Thx a lot for all of you!
The previous owner's family of my SAAB runs a BMW garage, and they filled in always M1 5W50. Probably reason is the Garrett turbo - oil lubricated shaft - likes to burn the not fully synthetic oils, furthermore, it operates at quite high temperature, so thick oil is mandatory especially on highways runs.

 

[Quattro Pete]

Originally Posted By: zoli
it operates at quite high temperature, so thick oil is mandatory especially on highways runs.

You do realize that a thicker oil actually results in higher operating temps due to increased friction?

 

[zoli]

Actually, my engine has high mileage now (218,000 miles), so the thicker oil fills the gap between the cylinder and the piston rings came from abrasion.
Aother thing: SAAB B205E engine has 'weak' oil pump, so thin oils are not recommended due to low oil pressure at low rev's.

 

[zoli]

Originally Posted By: stormy
... the shortest OCI with that oil would be 6k = 10tkm ... And go from 6k up to 7 ore 8k. The oil should be able to handle it:
http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=2243420#Post2243420

Hallo stormy!
Ich danke Ihnen sehr für die Analyse!

Great info on extended drain interval as well! Actually, I'm at the end of de-carbonation of piston rings came from applied semi-synthetic oils from last years, so this fill OCI will be shorter due to plenty of contamination inside.
This fully synthic oil - or HC synthese technology oil in Germany - also helped to reduce the oil burning 1 liter per 1000 km to approx. 1 liter per 5000 km.

 

[zoli]

The oil pan was dropped after 20,000 km (12,500 miles); last oil change (M1 5W50 and Shell 5W40 mix) 9000 km (5625 miles) ago: it kept clean the oil pan and cleaned the crankcase as well.

 

[Finn]

Is that oil pump pickup screen in your upper picture partially blocked by deposits or am I just seeing things?

 

[zoli]

It's just oil: (almost) nothing was on the screen.