DIY SEMI-SYNTHETIC OIL blend

[Bowman]

If I wanted to blend a semisynthetic oil myself, what ratio of synthetic to conventional oil should I use.
A local mechanic once told me a ratio of one quart synthetic and 4 conventional oil is all thats necessary.
I have a couple quarts of Mobil 1 5w30 and am planning on mixing it with Mobil SuperClean 5w30.
I run a turbo Subaru so think there may be a benefit to using the blend over straight conventional especially in the summer months. I change both oil filter and oil every 6 months averaging 12000 miles a year. I use a Napa Silver oil filter.

 

[renegade_987]

Any ratio of synthetic to conventional will create a blend

 

[pscholte]

I will only answer your question not argue whether you should do this or not. 3 Qts Syn/2 conventional is my rec but if you don't want to buy more Syn, NO LESS THAN 2 Qts Syn 3 conv

 

[RamFan]

Does Subaru recommend synthetic for that motor? If not, then they must not have seen the turbo react adversely with conventional. If you feel safer using a blend though, I'd blend 30% synthetic to 70% conventional. So for your 5 quart sump, 1.5 quarts of synthetic to 3.5 quarts conventional.

As a side note, most conventional today are in fact blends.

 

[Bowman]

My vehicle is a 2005 forester turbo. Back then they used conventional 5w30 oil and 3000 changes.

Having once owned a SAAB turbo, the dealer recommended only synthetic or the highest grade oils since the turbos 'cook' oil and fail as a result.

After my SAAB was totaled by my daughter after owning it for 14 years; we took the turbo and engine apart. I had been using Mobil 1 but changed the oil only once a year changing the filters every 3 months and adding fresh oil to level off.

Both turbo and engine were perfectly clean.

 

[JR]

Been. in enough turbo motors to say yes to hard on oil but i haven't seen coking or sludge ever. and most of my experience. is with engine ran exclusively. on conventional oil.

ken

 

[StevieBoy]

FWIW, my recommendation is at least 50% syn for a turbo. If it was mine I would go with 100% syn.

 

[Quattro Pete]

Originally Posted By: Bowman
A local mechanic once told me a ratio of one quart synthetic and 4 conventional oil is all thats necessary.

Necessary for what? I would say the ratio would depend on what you're trying to accomplish.

Quote:

I run a turbo Subaru so think there may be a benefit to using the blend over straight conventional especially in the summer months.

Wouldn't running full synthetic provide even more benefit then? Synthetic will flow better during cold winter starts, too.

 

[901Memphis]

Suburu turbo motors have quite a track record for being rough with motor oil. I would use at least 50% synthetic or just buy straight M1.

 

[fdcg27]

If I owned a turbo Subie, I think I'd spring for a full syn.
I'd probably consider Mobil 1 0W-40.
Even my NA Forester gets a full syn.

 

[Bowman]

I found the Warren MSDS sheets for semi-synthetic oil 5w30.

Additives make up 20% 10-35% grade 3 synthetic Remainder is Grade 2 base.

http://www.warrenoil.com/MSDS-Spec/PDS/W...Motor%20Oil.pdf

http://www.warrenoil.com/MSDS-Spec/MSDS/Warren/SyntheticBlendMotorOils.pdf

CITGO is 10%
http://www.docs.citgo.com/msds_pi/620851001.pdf

Castrol is ~40%
http://datasheets.bp.com/ussds/amersdsf.nsf/0/76E212EB9730DCC280257B430052739D/$file/194802Castrol%20GTX%20SynBlend%205w30.pdf

When I contacted other oil companies their replies were 'the information is propriatory'

 

[Bowman]

TG for Wikipedia

Semi-synthetic oil[edit]
Semi-synthetic oils (also called 'synthetic blends') are blends of mineral oil with no more than 30% synthetic oil designed to have many of the benefits of synthetic oil without matching the cost of pure synthetic oil. Motul introduced the first semi-synthetic motor oil in 1966.[1]

Lubricants that have synthetic base stocks even lower than 30% but with high-performance additive packs consisting of esters can also be considered synthetic lubricants. In general, ratio of the synthetic base stock is used to define commodity codes among the customs declarations of tax purposes.

Other base stocks help semi-synthetic lubricants[edit]
Group II- and Group III-type base stocks help to formulate more economic-type semi-synthetic lubricants. Group I-, II-, II+-, and III-type mineral-base oil stocks are widely used in combination with additive packages, performance packages, and ester and/or Group IV polyalphaolefins in order to formulate semi-synthetic-based lubricants. Group III base oils are sometimes considered synthetic, but they are still classified as highest-top-level mineral-base stocks. A Synthetic or Synthesized material is one that is produced by combining or building individual units into a unified entry. Synthetic base stocks as described above are man-made and tailored to have a controlled molecular structure with predictable properties, unlike mineral base oils, which are complex mixtures of naturally occurring hydrocarbons.[2][3]

 

[Shannow]

I wouldn't take wikipedia as the authority when it comes to trade practices.

David Vizard was IIRC the proponent of 10% synthetic (back in the days when it was synthetic) being cost effective performance. That's what I used back in the day.

 

[05LGTLtd]

If you're going to exceed the recommended poci by 50%, then I'd go full synthetic as several have suggested here already.

Seeing you're in ND, that makes winters interesting as far as an oil choice. If you are a Mobil 1 fan, then the 0w30 would be a better choice. Save your 5w30 for top off? I'd uoa at 4k, even on synthetic. You might be fine on TBN, but keep an eye on viscosity for shear. Mobil 1 30 grade oils get mixed reviews in turbo Subaru applications. Not saying it won't be fine for your situation, but if you are going to do an extended OCI, then verify.

Here is a short list of popular FI subaru oils that have good used oil analysis:

Rotella T6 (and T5)
GC
Mobil 1 0w-40
Pennzoil Ultra 5w30

I'm running BC 0w40 right now in the LGT, and on the second OCI. Have about 2200 miles before I am ready to uoa. Was on Pennzoil Ultra prior. No complaints with either, but I stick to 4k oci's.

 

[salv]

Don't mix oils with different additive chemistries. M1 and Mobil Super 5000 have different additive packages. They won't compliment each other. Go with one or the other, or just buy an already blended oil.

 

[Bowman]

So using 0w40 would be ok even though 5w30 is recommended. I thought that the 30 weight spec was a requirement since the 30 W would provided an adequate cushion for bearings while the 40 wt would be too thick.

So it would be acceptable to use xw40 instead of xw30 and still have adequate protection?

I am considering extended oil change interval yearly then, just topping off with synthetic with filter changes.
I average no more than 10-12k per year mileage.

 

[Bowman]

Originally Posted By: Bowman
So using 0w40 would be ok even though 5w30 is recommended. I thought that the 30 weight spec was a requirement since the 30 W would provided an adequate cushion for bearings while the 40 wt would be too thick.

So it would be acceptable to use xw40 instead of xw30 and still have adequate protection?

I am considering extended oil change interval yearly then, just topping off with synthetic with filter changes.
I average no more than 10-12k per year mileage.


ANYONE HAVE ANY TAKE ON THIS?

 

[StevieBoy]

I've been in N.D. for a couple winters. I would use Mobil 1 0w30 if I was there now.