Petrol mix with engine oil - 1991 Toyota Pickup

Could be a stuck open injector or a pressure regulator.

That other answer is suspect , If rings are damaged you will not get compression full stop , you changed head = the head or gasket ??? you should have run compression test just screw into plug socket , If your cylinder is down in compression, it indicates the problem cylinder, It can be due to rings or cracked head or bore , or gasket , come back when you know compression readings , If you have gasket blown the cooling water in rad will mix with oil and show foam . and compression, petrol mixing with oil is due to petrol not cutting off , where is petrol mixing in the sump?

if the engine is a petrol engine , you drain the tank and refill with petrol, you may have to bleed the fuel rail but basically it will run a bit rough to start with until all the diesel is flushed from the system then it will settle down
if it is a diesel engine and it is not performing on the bio diesel mix, drain the tank and replace the filter and refill with regular diesel
it may be a bit rough until the system is flushed
If it runs good just use the tank then refill with regular diesel

This problem is going to be caused by faulty injector o rings. You will need to remove and replace all 8 o rings on the injectors to correct this problem.The injector seals are the only place where the two fluids can mix unless a cylinder head is cracked.

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Thanks.

Smoke coming from exhaust is sign of a few things wrong. Either the petrol -air mix is not correct and rich fuel mix is going in. Worse oil seal leak. This means engine oil from sump is finding its way into engine cylinders and igniting with petrol. A sign that engine could be damaged soon. This needs to be addressed quickly - piston rings may be loose also.

Without knowing vehicle make or model it is hard to suggest anything further.

it is not supposed to, they should remain separate , your petrol is just lying in your sump at this stage, check your pipes, oil is usually circulated in the engine and goes little anywhere else , your fuel goes from the tank , through the fuel filter to the carburetor or injectors , and into the pistons , the closest oil and petrol ever has to meet is the small drop of oil remaining in piston chamber before combustion ,

Hi John, These days most oils are formulated to be used in both petrol and diesel engines but those formulated specifically for diesels should not be mixed. If your talking of a top up I suggest a flush with a good quality chemical and a lub service. If you have had a service carried out and changed the type of oil the same applies. Mixing oils can cause fast sludge build up which can block the filter, oil pump and galleries. These days most oils are designed to run both types of engine, but mixing is neve a good idea. Regards John

Hi Marsha, Many people mix brands of oil specified for either petrol engines and the same is true for oils specified for diesel engines if topping up, but it's not a good idea....It is a very bad idea to use an oil specified for one type of engine in the other. I would suggest never mixing oil manufactured for a diesel engine in a petrol engine or visa versa. The reason is that the diesel engine is dirtier than a petrol engine and manufactures of oil formulate it to have more cleaning chemicals than that used in petrol engines....Mixing the two can result in a build up of sludge which can actually block the lubrication system of the engine causing in some cases severe damage. Regards John

How did you determine that there is petrol in the mix? Oil and water mixing will show grey on the oil dipstick. Clear indication that you have a blown headgasket. Get the cylinder head off, have it resurfaced(at an engineering shop), new headgasket, reassemble, and Bob's your uncle you're under way again.

2 stroke engine 5% like on my litle motorbike.
don't go for that cheap oil that sticks.