Truckwash is a chemical cleaner you can water down and spray on before jet washing the trade use it a lot and works very well any valeting supplies will sell you it ,i buy 25 liters for £15 so not expensive and this is not watered down so lots for your money,you can buy it in 5 liters ,would spray on some wd40 on the leads dizzy etc and connetors ,mask up alarm box ,be prepared for it not to start after so you will have to clean and dry stuff out ,so you will need the car to be somewhere you can leave it,then when its dry you can repolish any ali as it will fade it and spray any bits that look tired