Diesel mixed with used cooking oil? Engineer's experiment raises concerns

There are people finding ways to save on fuel consumption amid the crisis, including an engineer who opted to mix used cooking oil with diesel.

In Mark Salazar’s report in “24 Oras” on Thursday, engineer and renewable energy advocate Ed Briones is mixing used cooking oil with the diesel as fuel for his SUV.

“Once na mayroon na siyang diesel, idadagdag ko na lang ‘yan,” he said, adding that his vehicle is still running normally.

(Once there is already diesel in it, I just add [the cooking oil].)

But the used cooking oil must be purified first before mixing it with the car’s diesel.

Ed has been doing this odd practice since 2019 and has never experienced any problems with his vehicle.

“From time to time, binabalik ko sa pure blend na diesel. Para papakiramdaman ko kung ano yung performance kapag pure diesel ulit; tapos after nun ibabalik ko ulit sa halo, ano yung performance,” he explained. 

(From time to time, I switch it back to a pure diesel blend. So I can get a feel of the car's performance when it’s back on pure diesel; after that, I return to the mixture and check the performance again.)

But Ed warned that even though it works for him, it may not work for other cars.

“Maari niyong subukan with disclaimer na you should do it at your own risk,” he said.

(You may try it, with the disclaimer that you should do it at your own risk.)

For its part, the Automobile Association of the Philippines said that such practice may not really save you on money as it may lead to further expenses once your car is damaged.

“It may help you save on fuel cost initially. But eventually, dudurugin niya yung mga injector ng ano mo, lalo na kapag common rail..Pwedeng gamitin yung mixture na ganyan kung direct injection,” said AAP President Joe Ferreria.

(It may help you save on fuel costs initially. But eventually, it will destroy your injectors, especially if it’s a common rail [engine]... That kind of mixture can be used if it is a direct injection [engine].)

While coconut oil is used in fuel mix, it’s only a small percentage and the blending process is sophisticated.

“Yung cooking oil mas mabigat yan kesa petroleum diesel. Kaya nagbabara, parang mas malapot siya kesa doon sa petroleum diesel. Kaya hirap siya gamitin ng ordinaryong makina. For modern engine, di pwede ‘yan, pero yung 1997 and below, ang tawag doon ay direct injection engines, ayun tatanggapin ‘yan,” said Ferreira.

(Cooking oil is heavier than petroleum diesel. That’s why it causes clogs; it’s more viscous than petroleum diesel. Because of that, it would be difficult if used in ordinary engines. For modern engines, it’s not allowed, but for 1997 models and below — what we call direct injection engines — those type of vehicles will accept the blend.)

Coconut oil was used by the Japanese during World War II, when car engines were still basic, due to lack of crude oil supply.

“Kung ang makina ay prior to 1997, most parts are more mechanical. Lalo na ang system diyan na tinatanong mo, anong klaseng gasket ang ginagamit nung araw? Gumagamit pa yata ng cork gasket nun. Thats the one used to keep the part sealed, yung rubber gasket, between two metal parts. ‘Yun yung nagbago,” said Ferreira. “Pangalawa, ang electronic components ng makina, nung araw wala nun.”

(If the engine is prior to 1997, most parts are more mechanical. Especially with the system you are asking about — what kind of gaskets were used back then? I think they were still using cork gaskets. That’s what was used to keep the parts sealed — a rubber gasket between two metal parts. That is what changed. Secondly, the electronic components of the engine — back then, those didn't exist.) 

“It may work, yes, pero dapat magaling ka na mag-mekaniko,” he added. 

(It may work, yes, but you need to be a very skilled mechanic.) — Vince Angelo Ferreras/BAP, GMA News