Inc, fluid type can also have a bearing on this.
I've had it happen (at idle, or close to it) when I had some Fuchs Dex II ATF after I'd flushed the OE Texaco/Caltex PAS 14315 out. The steering at speed was also lighter/less feel.... :?
Changed that out for some Calstrol Transmax Z (full synth ) and is virtually the same feel and response as the Caltex PAS fluid, although I reckon the Caltex fluid was better at very low speeds and in very cold weather, the Castrol is better when very hot.
Our Patrol has always done it....... :roll:
