Mixing oil

[dor]

My engine is recommended to use a 15:40 oil, CC/CD grade.

 

I've got some 10:40 and I've just been given some Duckams 20:50. Is there a problem mixing them, say 50/50, particularly with the higher 50 grade? It warms up quickly enough so I would expect the viscosity to drop smartly. The engine is based on a Mitsubishi push-rod engine and can't be any more sophisticated than a BMC 1800 of yesteryear which ran on 20:50 as standard.

 

Any thoughts people?

[cuthound]

The 10w540 and 15w40 are pretty much interchangable. The 10w40 will make cold starts a bit easier, both have the same high temperature performance.

 

The 20w50 is thicker when cold and when hot. Older engines had wider tolerances, and also fuel consumption and emissions were not such an issue hence they used thicker oils.

 

I wouldn't use the 20w50 on a modern engine.

[ditchcrawler]

Do Duckhams still do a CC rated oil?

[gazza]

Do Duckhams still do a CC rated oil?

 

 

No,

 

Thats a seriously old can of oil. i was using Duckhams Qi in my Capri in the late 90's, I think it stopped being available in 2009 odd.

 

Comma do an excellent 20/50 that we have been using for some time.

Edited May 20, 2016 by gazza

[Guest]

My engine is recommended to use a 15:40 oil, CC/CD grade.

 

I've got some 10:40 and I've just been given some Duckams 20:50. Is there a problem mixing them, say 50/50, particularly with the higher 50 grade? It warms up quickly enough so I would expect the viscosity to drop smartly. The engine is based on a Mitsubishi push-rod engine and can't be any more sophisticated than a BMC 1800 of yesteryear which ran on 20:50 as standard.

 

Any thoughts people?

Hi DOR

Honest answer is I don't know. I do wonder if a heavier grade oil might make the filter bypass for longer? Experts will know better than me. I agree the Mitsu S series is basically an old tractor/forklift/wagon fridge engine and might be OK, especially in summer, but I always use 15/40 (comma these days) personally. Used to use Asda 15/40 oil in the black bottles (Mobil) but they don't seem to sell it now.

As an aside, Vetus told me that this engine is OK on semi and fully sympathetic oil, and seemed to have no preference for any particular type. "Just use any good quality oil (of the correct grade.)"

[ditchcrawler]

My engine is recommended to use a 15:40 oil, CC/CD grade.

 

I've got some 10:40 and I've just been given some Duckams 20:50. Is there a problem mixing them, say 50/50, particularly with the higher 50 grade? It warms up quickly enough so I would expect the viscosity to drop smartly. The engine is based on a Mitsubishi push-rod engine and can't be any more sophisticated than a BMC 1800 of yesteryear which ran on 20:50 as standard.

 

Any thoughts people?

Its not the 20;50 that bothers me but the CC/CD but I can't see 3lt causing a problem in the life of the engine if its only once.

[Old Son]

Is this to save some money? How much would an engine cost if the oils are not happy together?

[nicknorman]

If this is Duckams Q ISTR from when you could buy it (in the 1970s!) that it was a bit different from most other oils and not recommended to mix.

[gazza]

If this is Duckams Q ISTR from when you could buy it (in the 1970s!) that it was a bit different from most other oils and not recommended to mix.

 

Different in so much as they ad a very good advertising campaign!

 

It was a good livery for touring cars too.

[Paul C]

No problem mixing them, the only effect would be that the 20w rating would mean the lowest ambient temp you can run at would be a little higher. But its May and you change it every 6 months, right?

 

More importantly how old is the oil? Oil has a shelf life and if its really old might have degraded a little already.

[DHutch]

As said 15/40 and 10/40 are fairly close, and particularly if elec start, likely to be fine assuming they are both of similar grades in terms of other additives. I would also have no issue putting in say 10% of the 20/50 either.

 

For me its not about cost saving, its about what do you do with the oil you don't use!

 

I have a 130k old BMW 330ci which does around a litre every 1000 miles and while for its oil change, and most top-ups, it gets the right grade. it also gets the odd pint of almost anything that is laying around and needs using up.

 

 

 

Daniel

[dor]

Thanks for your replies.

 

As Dan says, it is not so much the cost, it is the waste of otherwise good oil and its environmental implications.

 

I think I will use it, but at a bit less than 50:50. The CC/CD grade is right for the engine and I wouldn't be surprised if the engine was largely based on a western 1950s/60s push-rod engine - there is certainly nothing sophisticated about it. The engine starts easily even in the depths of a big freeze so I don't think the slightly thicker cold grade will be a problem.

[Guest]

Have you got a lot of it Dave? If it is only a bit you might be able to stick it in with a tank full of diesel and use it that way?

[dor]

Have you got a lot of it Dave? If it is only a bit you might be able to stick it in with a tank full of diesel and use it that way?

 

It's a full gallon can!

[Sea Dog]

There are no environmental issues in taking oil (whether new, used or of dubious origin) to the recycling center, tip or anywhere else with an oil disposal tank. There are to burning it in your engine via the diesel tank though, so it'd be a bit naughty to do that.

 

At the low price end of engine oil market where most of our boat engines sit, I can't see the sense in not using the correct oil in our precious powerplants.

[Paul C]

I'd just be worried about the age of the 20W50.

[gazza]

I'd just be worried about the age of the 20W50.

Me too.

 

5l of comma 20/50 in my local factors is £16.

 

Burn it in the diesel tank or take it to the tip.

[alan_fincher]

Can somebody provide a reliable source that explains why oil a few years old but still in the can is likely to be any less good than oil that was blended more recently.

 

I'm no expert, but I really can't see why it should be.

[Paul C]

https://www.yourmechanic.com/article/what-is-the-shelf-life-of-motor-oil

 

http://www.brighthubengineering.com/fluid-mechanics-hydraulics/100685-extended-storage-of-synthethic-motor-oils/

Edited May 21, 2016 by Paul C

[cuthound]

When I worked for BT I was part of a team that looked at reducing the cost of maintenance.

 

By using oil sampling to measure contamination, we pushed the oil changes from once a year to every 6 years for the standby generators. There was no sign of the oil breaking down in this period, only getting contaminated by combustion products.

 

Note however that because the engines were located inside buildings, and had crankcase heaters fitted to enable them to take full load from a cold start, there were no issues with condensation contamination, which increases the acidity of the oil.

 

The engines usually only ran for a few hours per year as well. However if they were called to run in anger, the oil was changed every 250 hours.

[OldGoat]

10/40 tends to be semi synth and Beta told me - on no account use that in 'our' engines.

No reason given - possible doubts about the dreaded bore glazing??

Now I've got a lot more than 5l of 10/40 hanging around.....

[Guest]

10/40 tends to be semi synth and Beta told me - on no account use that in 'our' engines.

No reason given - possible doubts about the dreaded bore glazing??

Now I've got a lot more than 5l of 10/40 hanging around.....

I have noticed that mineral oil is getting a bit harder to find. I get mine from a local agricultural /truck parts supplier at a very good rate on 25 liter price (filterers too for a five pack.) By buying in these qauntities it works out that I get one oil change for free (important for a Northener )

[Tony Brooks]

I am very wary about "semi-synthetic" claims.

 

I do accept that in very high performance engines basic mineral oils will simply not do the job required so chemically engineered liquids are used but all oils contain an additive pack, even API CC ones, and the additive pack "beefs up" the basic mineral oil. The pack is produced by other companies and is blended with the oil. What is in the pack I have no idea (I do know some of the jobs it does but not what it is) so it is reasonable to assume it is a blend of chemicals that are not basic mineral oil. Now, since the high profile marketing of things like Mobil 1 "everyone" knows that synthetic oils are the best you can get so I would not be surprised if semi-synthetic is nothing more than a marketing ploy that in reality refers to the additive pack.

[ditchcrawler]

 

I am very wary about "semi-synthetic" claims.

 

I do accept that in very high performance engines basic mineral oils will simply not do the job required so chemically engineered liquids are used but all oils contain an additive pack, even API CC ones, and the additive pack "beefs up" the basic mineral oil. The pack is produced by other companies and is blended with the oil. What is in the pack I have no idea (I do know some of the jobs it does but not what it is) so it is reasonable to assume it is a blend of chemicals that are not basic mineral oil. Now, since the high profile marketing of things like Mobil 1 "everyone" knows that synthetic oils are the best you can get so I would not be surprised if semi-synthetic is nothing more than a marketing ploy that in reality refers to the additive pack.

 

You are defiantly as cynical as I am Tony.

[Guest]

Well, well, just cleaned the shed out (is it that time of year already?) and found some old but unused synthetic engine oil! Must be from when I had my Shogun so at least 5 years old. No good for my boat or my current ford (Zetec) so gonna burn it off in the diesel on the boat. What is the maximum oil ratio I can safely burn?

(12 litres to use up in Vetus/Mitsubishi engine.)

Many thanks.

Edited May 22, 2016 by Guest