Mixing conventional/synthetic

[90Notch]

Hello,

I'm new to this forum and had a question about mixing synthetic oil with conventional. Is it ok to mix three bottles of Castrol 5w30 with, say, a bottle of Mobil 1 synthetic 5w30? The wording on the back of the Mobil 1 bottle says it's ok to mix with conventional oils. Is there an advantage of mixing in one bottle of synthetic every oil change?

 

[mikemc]

I don't think there is any problem, but not sure if there are any real benefits either. Conventional oils have really improved over the last few years and are giving excellent results in drain intervals of up to 5,000 miles.

 

[Jay]

The problem with mixing different brands and types of oils is that you have an untested, experimental oil. Synthetic oils profess compatibility with conventional oils, and they are compatible, but that doesn't mean that the mix is optimum. Chances are that you could have better results without the synthetic in the mix. Only careful testing will tell you for sure.

 

[90Notch]

I figured since there are synthetic blends out on the market, I could possibly get similar results by mixing them. But, as you stated Jay, only a test will really tell me if it's beneficial.

 

[haley10]

Why not use Castrol Syntec Blend or Mobil Clean 7500? They are fully formulated and tested already.

You won't do any harm, but I doubt any improvements over the formulated blends. It a pig in a poke as opposed to a tested product.

 

[1sttruck]

Using the previous examples 100% synthetic is a $3.20 premium over dino, while the typical 15% or so synthetic in a blend is a $1.00 premium over dino; you pay about 31% the premium for about 17% the amount of synthetic.

My own blends cost about the same but I get 40% of Truck & SUV, so I pay 31% the premium for 40% of the amount of synthetic.

Seems like a better deal to mix your own.

 

[Cyprs]

I talked to an Esso/Exxon tech and he talked to an Esso engineer on this question I submitted on Esso products. I asked if I could mix 0-40 XD3 syn with XD3 15w40 conventional. The main jest given back was to stick with brand and type oil, meaning go XD3 in both syn and dino with the same "hot" number, in this case 40 weight. the cold weight is of not real significance, it is cold start weight for cold start, the heat visc at 40 or 30 should be same as well as oil type according to tech people.

Basically keep the hot (second weight) the same, dont use Esso Protec dino with Esso XD3 syn, stay with the same add pack in similar sisters in conventional and synthetic oil, for example in XD3: CI-4/SL syn to CI-4/SL in dino content, or SL to SL etc. this is what I do, after my breakin with dino XD3 5-30 in new nisssan I will go to 50/50 5w30 conventional to 0-30 syn in XD3 for one OCI, then Full Synthetic XD3.

On my diesel I go full strength XD3 0-40 syn winter and 33/66 syn to dino with 0-40 syn to 15w40 conventional XD3 summer. I buy my dino content in bulk on sale, I do this 33/66 blend for same price as regular price on full dino OCI based on a 12 liter OCI on Cummins.

I understand it is not advised to mix syn oils, syn to dino is usually accepted, I mix them apples to apples though in brand, weight and add pack.

I mix my own for one reason, companies do not state synthetic blend percentage content, I read in here oil companies can put as little as 9% syn oil in a blended oil, their price we reflect 50/50 blend in pricing.

Cyprs

 

[Triple_Se7en]

I read in here oil companies can put as little as 9% syn oil in a blended oil, their price we reflect 50/50 blend in pricing.

Here in Lower Michigan, name brand synthetic blends are usually $1 more than it's dino relative.... nowhere near 50% higher. A typical non-sale here would have...
dino at $1.79
syn-blend at $2.79
full-syn at $4.99

Just curious! Retrieve us three prices ... ie... from either Castrol, Pennzoil... etc & give us the price differences in your neighborhood between dino, syn-blend & full synthetic. I'm suprised to read that "blend" is so expensive there.

 

[Cyprs]

Up here in Canada I have spent lots of time on Walmart shelves comparing dino, Synthetic Blends and full synthetic oils.

I find this, if brand X dino is 2.00 litre and the brand X syn is 6.00 litre, the syn blend in that brand X will come in around 4.00 per litre, if that brand X semi syn was a 50/50 blend, I consider it fair value, I question the syn blend ratio, is 4.00 per litre worth it not knowing the % blend? I prefer to do my own and know what is in my engine. Synthetic Blends should be required by law to give the percentage of syn to dino blending IMO, then and only then can the playing field be level, I believe oil companies keep the blend % silent for their advantage, an advantage I will not give them personally.

Cyprs

 

[Blue99]

Off-hand, the only actual synthetic blends I can think of, are Mobil Clean 7500 and Schaeffer's. Maxlife is reported to have some PAO, but it is not advertised as a syn blend.

The "synthetic" in most synthetic blends, Castrol, Pennzoil, Havoline, etc. is GRP III dino, and with GF-4 oils, I think the product has about hit the end of it's marketing life cycle.

 

[TCP442]

I've been changing my own oil for 35 years....wow has it been that long!!...the last 10 years I've been " mixing" 1 Qt. Mobil 1 with a variety of Conventional oils ..I NEVER had a problem of discoloration, separation,sludge, varnish etc, and believe that the Mobil 1 gave me an "edge"...in other words I use it as an additive...results= near 200k on "88 vulcan sable", similar result on 86 Civic, and now using in "99 Camry 4 cyl....My view , however to " play it real safe" has been to use Mobil, or even better Exxon dino in the same spec ( sl..sm ..etc) as the Mobil 1....I personally dont like the " blends ' as they are very evasive as to the content % of synthetic...

 

[GROUCHO MARX]

Mix away you mad scientist.