15w40 with Risolone to fix seal: Is 15w40 safe to drive?

[99 TACO 3.4]

Risolone makes a product (500 ml) which added to non-synthetic oil 15w40
can stop leak in the rear seal between back of motor and transmission.

I have to drive next week 2,000 miles from Mexico to Florida so I changed the oil
to 15w40 and the 500 ml of Risolone. IT WORKED. Seal is no longer leaking.

My question is CAN I DRIVE THE 99 TACOMA 3.4 for this trip using the 15w40 and
Risolone?

Or, DO I NEED TO CHANGE BACK immediately to synthetic 5w30?

Thanks. Can't take any risk of the 15w40 oil causing an engine failure on the road.

 

[TacoTruck2019]

Safe????? Can't really give you a truthful answer other than I wouldn't do it. I'd go with a high mileage 5/30.