Would it be ok/compatible to mix 5qts Magnatec 5w30 with 1qt Edge EP 5w20 or should I just run out and grab a sixth quart of the Magnatec. The vehicle calls for 5w20 so I'm not concerned about the Edge thinning out the Magnatec. This is in an 08 Mazda CX-9 w/ 90k miles. Thanks.