Chances are with that mileage you have worn valve guides and the top up is being burnt in the cylinder because of the added pressure.
You would notice it more on start up from cold and when backing off the throttle tbh. When you're not on the throttle you're not burning fuel so the oil would get burnt and be more visible.
Try getting someone to follow you to see when it happens as you can always tell when driving.
If you'd blown a gasket you'd either get white smoke from water being burnt in the cylinder (steam) and a rapid loss of water or a lack of compression in a cylinder which would run lumpy and not make power so I doubt if its that.
You would notice it more on start up from cold and when backing off the throttle tbh. When you're not on the throttle you're not burning fuel so the oil would get burnt and be more visible.
Try getting someone to follow you to see when it happens as you can always tell when driving.
If you'd blown a gasket you'd either get white smoke from water being burnt in the cylinder (steam) and a rapid loss of water or a lack of compression in a cylinder which would run lumpy and not make power so I doubt if its that.