I'm about to change the oil on my aunts 1998 Toyota Tacoma 2.4L with 235k miles and it's been run on synthetic, I was thinking Pennzoil Platinum but I don't know what weight it takes? 5w20 or 5w30?
I run 5w30 Mobil 1 in my 04 Tacoma at 5k OCI. Been doing that since it was brand new and never had any engine issues. 5w30 SN is spec for year round protection in the Tacoma's. I would also recommend picking up an OEM Toyota filter. They seem to work better for me, especially at startup.
I purchased a 00 Tacoma 2.4 new in 2000. Put 187k on it in 4 years. Used M1 5/10w30 until it was sold. The engine ran like a top, never consumed a drop and the emissions read lower than average. In 00, I was not quite the most savvy when it came to oil and used to change it out at 3k. If I had a 2.4 now, I'd run 8-10k OCI's.