So our GX325 is due for an oil change. It is an 18 hp Kawasaki engine. Last year I bought a kit for $45 that had spark plugs, air filter, fuel filter, oil filter and 2 qts of Turf Gard 10W-30 that I used. This year I just plan to change the oil and filter and was wondering with all the changes to oil if there was a better substitute? I found this on a John Deere Question/Answer website: Question: What type of oil should I use in my John Deere Lawn Tractor (Gasoline Engine)? Affected Equipment: All Riding Lawn Equipment with gasoline 4 cycle engines Answer: In general, for gasoline engines you should select your oil based on the expected air temperature range during the period between oil changes. The following John Deere oils are preferred: Turf Guard 10W-30 Plus-4 10W-30 Other oils may be used if John Deere oils are not available, providing they meet one of the following specifications: SAE 5W-30 API Service Classification SG or higher SAE 10W-30 API Service Classification SG or higher SAE 30 API Service Classification SG or higher Synthetic engine oil can be used in Lawn & Garden products, but we recommend waiting until the second oil change interval (about 50 hours) to switch from petroleum-based engine oil to synthetic oil. This ensures that the engine is thoroughly broken in. If synthetic oil is used, continue to use the viscosity recommended in the Operator's Manual. Note: The use of synthetic oils such as Mobil 1 is acceptable; however, you must change the oil at the recommended service intervals as outlined in the Operator's Manual, NOT the extended intervals as described on the oil bottle. When adding oil after an oil change add oil no higher than FULL mark on dipstick. Use approximately the amount of oil listed in the Specifications section of your operator manual. Do not overfill. For oil capacity please reference your Operators Manual. Some operator's manuals are available online. To purchase John Deere oil please see your nearest John Deere Dealer Learn More on John Deere Oils and Lubricants https://groundscare.custhelp.com/app/answers/detail/a_id/262/~/type-of-oil-(riding-lawn-equipment) Conventional, synthetic, a different weight? We live in PA and mow an acre of grass a week and then it sits all winter so it is not used hard. I never have to add oil so maybe I should just stick with the Turf Gard. Also, I have a Super Tech 4967 filter that was for a car I traded years ago. I cross referenced it to the John Deere AM107423 filter so I was thinking I may as well just use it. It is about 7 years old. Any concerns with this filter?